Lot's of interesting comments here... my thoughts are now scattered in different directions since each makes sense in its own way.
Here are some of my take-aways from what folks have mentioned =
these are ideas below on how starting with "purpose, stakes, and limitation" can apply to all player types, and not overload with info or whiplash change lore. And greatly enrich any game and any setting for fantasy.
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"We can't make realistic lore..."
This is a amalgamation of a few comments, but the general talking point here is:
"How can we make lore more than rules or window dressing?".
To that I say, again, we look to some good Sci-Fi. As other folks have mentioned here, sometimes it is just clarifying the "Why" each feature exists in a fantasy world. We keyed in on races here since they are obvious 'nails', but magic and geography are true targets for this too: in that, when a given setting says "we have elves", i think its fine to say "ok but why?".
Setting aside the "because I want them" or "because people expect them" (those are fine reasons, but they are not solving for anything so no need to address them).
We
answer any given fantastical element with "We study all kinds of species on Earth, and many have their own habitats, breeding practices, and even in many cases 'traditions' passed down by elders" if our common animals here do this, then its perfectly valid to assume "Tengu" or "Elves" or whatever - do so even more. And if they are based on an animal, then we even have a guide for how they might have evolved and established their lives over time.
So yes, we 100% can think of "alien races and their alien cultural progress", there are tons of ways to translate animals to humanoid beings and then run with imagination from there. We see this somewhat commonly done in Sci-Fi.
"It would be too much to read."
Or some other such concern about overload of lore. And I get that, I 100% do. But this is really just a matter of what someone else said here = "No,
you can 100% have realistic and thoughtful lore, and keep it concise and relevant."
This concern for "too much exposition" sometimes comes up in films too, where folks will say "Hmmm, they didn't explain X". And others will reply "Well we don't want 45min of exposition." And i agree!
But exposition, and 100 pages of history is
not the only method we have for presenting lore that has consequence and functional purpose.
There is a rather marked difference in =
A (the typical fantasy way): "Tengu are humanoid beings that have feathers and bird heads and biology like birds to lay eggs. For X years Tengu suffered as a persecuted and embattled underclass. They now live amongst humans as part of X wars and tribal states. Their living areas resemble poorly planned networks of slums. Most see them as little better than thieves and cutthroats."
= there is
no purpose here, other than the odd way they look, we could have just used humans from country X.
and...
B (the typical sci fi way): "Tengu eggs are prized for their flavour as well as the shell colors used in jewelry and pigments. The most valuable and rare of their eggs eventually bred higher thinking and more humanoid Tengu. X years ago, they broke free of their enslavement and formed their own tribes in lands that would accept them, the humans - even if only as second poor serfs and peasants."
= This still tells us they are bird-people, but it gives us WHY they are relevant in the world AND how they came to be - all in the same number of words! So no lengthy exposition needed to give Tengu both
evolutionary purpose and cultural relevance that
no human culture could replace.
...also...That's just an
example, please don't rush to "but I don't want
that history/reason"
So this also
fixes the "too much history" problem. Because we don't really need the details of their enslavement, and their wars. Unless that is relevant to the plot, we can let that be assumed or filled in later. We got why and how they exist at all and how other races see them - and that is what matters most.
History events and Encyclopedic exposition are all that makes a fantastical aspect have purpose.
(Some folks like this verbosity, and that's fine, let that go into some other rich setting and history book. Historic events are only a
part of 'purpose'... we can't skip over the reason for why it started/exists at all.)
"The worlds never make any sense"
What option B does is also help paint a world like FR/Golarion make sense. Instead of other races popping up as just a matter of who the heck knows why, or the gods said so, we have a shared existence and evolution. One race, humans, acknowledged the other, Tengu, and did want humans do often - exploit. And this is made even more plausible by the biological reasons and differences.
We didn't take extra exposition, and we didn't change the fact that Tengu are playable humanoids. So no loss of anything that fantasy tropes need.
Now imagine a world of Tengu, Tieflings, Naga, and so on... each with that little bit of purposeful place in the fiction, each with some acknowledgement of the others as part of their ecosystem and evolution.
We
avoid trite situations where a Tengu who
looks and functions most every part of the 'bird', but is
treated like any another window dressing of 'that farmer over there but feathered'. (because we never gave their
species purpose in the world).
Much of the sensation and feeling of wonder and fantastical in Babylon 5 was how they addressed different alien habitats and physiology.
Why can't fantasy do that too?
"There was a cataclysmic event"
Naw, that changes little to nothing. And talk about an over used trope
Even if tomorrow nuclear Armageddon hit earth, getting back to 2000s tech would take less time than it did in the first place. Remnants of tech, repositories of knowledge, surviving people - all contribute to an accelerated resurgence of what comes next. Sort of a total slate, utter wipe out of all species and planet biology, a lot remains to build on. And magic makes this even more prevalent.
I am ok with "forever stuck in the middle ages", its not a bad time or patina of setting. But that is no excuse to make the setting a literal copy-paste when you have Tengu, Tieflings, and other such beings who likely never developed a setting were medieval Europe's look and function ever happened.
Good heavens, how much would
the world look different at every level in the Age of Sail; if there were two utterly incompatible humanoid sentient species on the planet with different biology! Not to mention real world-walking gods...
So, ya know... let's ditch the grey castle in Saxony, and utterly unchanged king and queen tropes; and maybe go back to the whole 'purpose' thing and consider art, architecture, and culture of beings who have bird biology or whatever biology a tiefling or naga has.
..............
To me, this all comes back to compelling games. Games I want to play. I demonstrated above how giving a fundamental purpose and limiting boundaries on lore make a setting more connected, and functional at a core level. And nothing was lost from it.
I am not sure just playing "middle ages with costumes as people" is enough for me...