I may be a boring GM when doing fantasy campaigns, but I prefer my players characters to be human, or at most one of the Tolkien races. The reason for this is simply that I have yet to meet a player who can play an ”exotic race” character as anything other than a human with bad makeup and some cultural quirks. I like to think that I can contribute to make my PCs feel special and unique without them having to be a ghost fairie etc.
I realize that I’m old and that the current fantasy paradigm is way more expansive when it comes to race/speices/heritage. I’m not into it.
Dragonborn are, of course, one of the most obviously non-human races in the game, after all, they've got scales instead of bare skin and ropy scales instead of hair etc. But the only major differences between them and humans (per the 4e lore, as 5e has...kind of avoided much strong lore about non-Tolkien-eque races) are that they eat a larger share of protein (so they need different food sources); they mature earlier than humans, so they can have slightly faster generation turnover (assuming sufficient food); and because they lay eggs, women can be warriors just as much as men, especially when paired with wet-nursing. In terms of sociology, economics, and warfare, dragonborn are basically identical to humans.
A single elf being able to collect wealth for ten bloody times the amount of time a human could? An enormous economic difference. Sociologically, can you imagine how different politics would be if we had to deal, not with the politics of people born in 1940, but people born in 1340? These are people who might be annoyed that the government stopped using French...because they remember that the Parliament of England used French after 1066's invasion by William the Conqueror. They lived through the Wars of the Roses. For them, Shakespeare was a provocative newcomer that these damned kids have normalized. For them, the greatest conflict would probably be Christendom vs Islam, for goodness' sake! Their grandparents would've been Roman citizens!
We've handwaved the incredible alienness of elves (and to a lesser extent dwarves; remember that since they live 200-300 years, for them, the US Civil War is still in living memory) simply because we think we know them well due to Tolkien. Dragonborn and tieflings, in looking more different and not having the titanic juggernaut of Tolkien behind them, can easily feel more alien despite practically being much more similar to regular ol' humans.
Or, to put it differently: We became so obsessed with the rubber foreheads, we overlooked how alien "actually 700 years old" would be.
A single elf being able to collect wealth for ten bloody times the amount of time a human could? An enormous economic difference. Sociologically, can you imagine how different politics would be if we had to deal, not with the politics of people born in 1940, but people born in 1340? These are people who might be annoyed that the government stopped using French...because they remember that the Parliament of England used French after 1066's invasion by William the Conqueror. They lived through the Wars of the Roses. For them, Shakespeare was a provocative newcomer that these damned kids have normalized. For them, the greatest conflict would probably be Christendom vs Islam, for goodness' sake! Their grandparents would've been Roman citizens!
i'd like to what would get created if the mould was broken a little more and the tolkien core four/five and their well-worn dynamics weren't inserted into every setting as default, what might you get with a setting where your baseline species are a lineup of, say, dragonborn, gnomes, kobolds, satyrs and warforged and that humans, elves, dwarves, halflings and orcs were nowhere to be seen.
To be far, there are parts of the Forgotten Realms like that. Kara Tur had very few "demihumans" like Elves and stuff although that appears to be changing.
The Old Empires Region had more Tieflings and Aasimar then Elves, Dwarves, and Halflings, although to a lesser degree in Chessenta.
my point is that for teiflings it is irrational for them not to be mostly human unless they are derived from a different base.
However, your point existed more out of a lack of definition, the other options are harder to rp as they are less defined thus if they where better defined, you would likely have less of an issue.
Well, if it helps any, I've "spoken" (over forums) with several people over the years who would want to call the RPG police over someone wanting to play dragonborn. As I've mentioned in a previous thread, there was even a "D&D Next" article (long since lost in the multiple WotC websit purges) which openly validated folks who wanted to completely exclude dragonborn and tieflings from the 5e PHB. So, at the very least, whether this was tongue-in-cheek as it appears or not, there's some similar worries from the "other side" too.
I take roleplay very seriously. Too seriously for a fair few, I imagine. But I also know that xenofiction is rare and difficult, and good xenofiction doubly so. Hence, I expect any playable species/race/heritage/etc. is going to have several things clearly relatable to we human players, and a sprinkling of things that really are different and require thought.
As a result, comments in the vein of what you said tend to frustrate me, because they feel like they're presenting a kind of unfair, impossible standard. On the one hand, they argue that any trulynonhuman character must be genuinely inhuman, that is, so deeply unlike human beings that there is an inherent gulf of understanding that either can't be bridged, or is extremely difficult to do so. Anything less is "just a human with a rubber forehead", and thus not worthy of being played. But then the impossibility component kicks in: the assertion that something truly alien is something we can't really understand or relate to, genuinely sundered from not just common cultural norms (since <this could be an Earth culture> has been said to be inadequate) but actually outside our ability to even think about, and thus incapable of being played.
Thus we get the self-fulfilling prophecy: if it's alien enough to be worthy of being played, it can't be played because we're humans and only know humanity; if it's playable by a human, then it's already human enough to just be a human, so it isn't worthy of being its own thing, just play a human. Sort of a Morton's fork.
And I reject that line of reasoning. I see it as a Venn diagram. There is the space of all theoretically-possible experiences; "possible for a human" is a circle in that space, and "essential to human-ness" is a smaller circle wholly contained within it. "Possible for a dragonborn" is another circle that has substantial overlap with the first...but not total overlap, and same goes for "essential to dragonborn-ness" and the second. I find it fascinating to explore that boundary line.
Some good examples from my own ponderings on the lore for dragonborn provided in 4e (since, as noted, 5e has been...scant with it at best, and much of it legitimately just makes dragonborn more boringly human-like!):
Dragonborn mature faster than humans. They can walk within hours, they're the size of a human pre-teen at age 3, they finish the core changes of puberty around the time humans now start puberty (roughly 12), and they're full physical and mental adults by age 15. That's precipitous growth followed by long plateaus. Dragonborn children are almost never helpless once they leave the egg stage, making them far more mobile and easier to protect, but also prone to risk and injury due to lack of experience. Infancy and early childhood are genuinely things you can miss if you're away for mere months; a child's first steps aren't really a huge milestone because they happen so early. Etc. This would produce a very different cultural attitude about the meaning and context of childhood, even though both humans and dragonborn go through more or less the same childhood experiences, dragonborn just have them faster. (I humorously liken them to anime children: where for a human it is pretty ridiculous to have a hardened, world-renowned tactician at age 13, for dragonborn, that's just a slightly precocious lass.)
In 4e, dragonborn healed faster than other races (in 5e terms, they added double their Con mod to Hit Dice rolls, more or less.) This, when paired with their explicit description of needing a higher amount of protein than humans, and their physical description of being tall, broad, and highly muscular (an adult dragonborn is somewhere between 185 and 205 cm, clocking in around 100-150 kg; for my fellow Unitedstatesians, that's ~6'1" to ~6'9", 220-330 lb.), implies that they have faster metabolisms, and specifically that their bodies use and process protein faster than humans--significantly so, allowing them to both build muscle mass faster and spend less time recovering from injuries. Given human sensitivity to disease and infection, plus dragonborn children essentially skipping over the "fragile infant" phase, dragonborn would be noticeably more resilient against most of the things that literally and figuratively plagued humans for the roughly 12000 years prior to the advent of modern medicine.
Naturally, dragonborn produce breath weapons on the regular. Even if it's only a percentage of the population, this entails all sorts of significant sociocultural concerns that look like just being a different Earth culture, but which are rooted in their physiology. For example, prisons. You can't just hold a prisoner behind a plain old wooden palisade, because their breath weapon will almost certainly be able to destroy or weaken it enough to let them escape. Even bronze or iron aren't reliable if the prisoner can subject them to repeated breath weapon attacks. You'd need sandstone or other truly inert building materials to ensure belligerents stay where they've been put--or some way to reliably suppress breath weapon usage. This, then, gives a physiological root for why dragonborn would develop an extremely strong "honor" culture: they literally couldn't reliably imprison people in a low-tech society, so they would need some other kind of limitation that would regulate behavior and permit a stable, functional social structure.
Dragonborn may have tails. (Canonically, they didn't...but even back in 4e that was being ignored by half the players anyway, so WotC wisely gave up and just said dragonborn may or may not naturally possess a tail.) Generally, when they do, it's depicted as a pretty chonky thing, like what a bipedal dinosaur or crocodilian might have, rather than the whip-like tail in most mammal species. That's going to result in various behaviors, cultural norms (how does one use one's tail? Do others pay attention to it, or pay it no heed, or actively avoid thinking about it? Is it to be decorated, or left bare?), and physical consequences like the design of chairs, leg/butt clothing, and
Being draconic, dragonborn are typically depicted as not possessing proper hair, never sweating (instead using their large mouths for evaporative cooling), and having a layer of scales (somewhat fine in most places, thick at joints) which provide extremely minor resistance to tiny, incidental harm (e.g. they probably don't get papercuts). As a result, would they view clothing differently? They don't need to wash nearly as often, as they don't sweat, and their scales shed more slowly and obviously than human skin does. Their scales may provide very minor sun protection, meaning they might not need to cover themselves--and many societies that live in warm climates don't bother covering themselves anyway. When coupled with their low degree of sexual dimorphism and other plausible reptilian traits, they might not have nearly as strong of taboos about nudity, or might wear significantly less clothing than humans--or perhaps more clothing, to help keep heat away from their bodies, like what the Bedouin peoples wear to stay cool in the desert! Either answer has reasonable explanations, so picking one and sticking with it is important. (Or perhaps there are gendered or sociologically-induced lines. Perhaps wealthy dragonborn wear as little as they can get away with, because they don't have to go out into the summer sun, and thus remain cool naturally, while poor dragonborn wear a lot of clothing to protect themselves from the heat; this would imply a beauty standard based on minimalism rather than ostentation as is normally the case in human cultures.)
Some of these I've spoken of at length before. Others are ideas I've previously had, articulated better. Point being, there can be significant differences....even while there are also significant similarities. Paying attention to subtle details, extrapolating (and supporting) plausible cultural impacts arising from known physiological characteristics, and reflecting on how a single individual person can be affected by those impacts differently (e.g. some embrace, others endure, some defy, and a few try to crusade against)--that's how you get really sincere, authentic roleplay of something that you partially, but not fully, relate to.