well in the real world we already break down things into Order-Family-Subfamily-Tribe-Genus -Species-Subspecies
Primate-Hominidae (great apes)-Homininae-Hominini-Homo-H.Sapiens-H.Sapiens sapiens (Modern Humans)
The fact is species isnt clearly defined and the borders between species and genus are permeable, especially when you also get the issue of morphs (same species different phenotype) which probably applies to Elfs in particular. So yeah assuming they're all mammals Orcs-Elfs and Humans are certainly the same Family, maybe evensame Genus with species proliferating from there
Taxonomy has been rejecting what they teach us in grade school about Domain-Kingdom-Phylum-Class-Order-Family-Genus-Species for decades now. Cladistics is where it's at.
If we accurately represented Birds in the old Linnean binomial nomenclature, the ENTIRETY of the Bird Class would be a single Species of Dinosaur. So we either have to accept that the system is biologically bunk and can't represent actual proportional distances of relationship between thingys and we're just decided some thingys look different enough that we're starting over at a higher level of the system with them, like Birds, or else we need to throw it out and replace with visual diagrams of endlessly nested and cross-pollinating lineages.
Even modern humans are believed to be chimeric descendants of
Homo erectus that developed into
Homo sapiens in Africa, Neanderthals that separately split off from
Homo heidlebergensis in Europe (whom probably split off from
Homo sapiens in Africa before we'd call them separate from
Homo erectus), and also Denisovans who are a third branch that may or may not have split off from
Homo heidlbergensis or else from
Homo erectus separately. Should we consider Denisovans and Neanderthals and H. sapiens as subspecies of H. sapiens, a la H. sapiens sapiens vs H. sapiens neanderthalensis? That sounds terribly close to 1800s racist "subrace" theories. Should we instead say it's just a mish mosh pool of confusion that spread out from
Homo erectus at a certain point? I'd argue for this second path of action, but it doesn't help those trying to actually tell the story of who the Neanderthals and Denisova were and how important it was that these groups merged into certain populations of the core spine of
Homo sapiens who make up the bulk of modern Human DNA in every one of us. And more importantly to the discussion, it doesn't help the Half-Neanderthal fans who want to play a Half-Neanderthal and are told, no, make either a Human or a Neanderthal and call them a Half-Neanderthal. Where Neanderthal is a stand in for Elf or Orc, obviously, but I don't mean to suggest that Neanderthals are elvish or orcish or half-elf fans are like cave men or stupid, nor do I mean to suggest that Neanderthals were stupid as they were clearly a very intelligent and wise people who likely just diffused into Eurasian DNA like any ancestor would over countless generations.
In any case, it's a question that we don't really need to get into any deeper in D&D, since no Player really wants to draw cladograms of the PC character options and how they all come ultimately from the same original stock of Plasmoids in the Astral Sea that crash landed in the Barrier Peaks… err… I mean…
If you ARE a player and DO want to draw those cladograms, you're probably a DM-in-waiting. But that sort of nonsense belongs in your campaign bible, NOT in the Player's Handbook or even the DM's Guide (or GODS-NO, not the Monster Manual, lest we get into discussions of the cladistic ancestry of Chimeras or even the Chromatic Dragon herself - is Tiamat a Draco rufus x azul x viridi x alba x tenebrae 5-species hybrid!!?). What we NEED in the Player's Handbook is a term that can allow subterms to exist for flavour text (a la, Eladrin are a sublineage of Elf), while allowing those subterms to stand on their own two feet as the prime term (ej. Eladrin is a lineage you can pick, and Elf is a lineage you can pick), while also allowing them to exist as a mechanical subterm (ex. Elf is a lineage you can pick and Drow is a sublineage of the Elf lineage that you can pick), while also not being demeaning (aka your Drow is SUB-Elf and that makes my full-Eladrin better than you… it's the same reason there are no sublineages of Human; we don't want suggestions of subhuman).
Species PROBABLY doesn't work here for the problems I identified above with Denisovans; claiming they're subspecies of Human suggests, even if innocuously, that these Denisovans are subhuman, and thus their descendants (largely people of Asian and Pacific descent) are subhuman by correlation. That's just REALLY icky territory we all want to avoid, even if we're not realising it when we throw around the term species and subspecies in regards to Elves and Gnomes and whatnot. It has an impact, even when you keep Humans out of it for obvious reasons (skin tone should have 0% mechanical impact on your character, full stop). Because Elves are a classic proxy for Humans. And Drow are dark-skinned, and Wood Elves can be pale North european-to-barky-brown skinned, but High Elves are almost ALWAYS portrayed as light skinned (though in my homebrew, High Elves have reddish-bronze to black skin as are closely associated with the Sun Gods, while Pallid Elves and Astral Elves are the pale ones associated with the Moon and Stars).
But in general, Drow are defined visually by their dark skin in relation to other Elves light skin. While skin tone may not be mechanically relevant to Elves, it correlates with their sublineage choice. And calling Drow a subspecies of Elf IMMEDIATELY creates the idea that they're inferior than "the default" Elf options we encounter above ground - the High Elves and Wood Elves in the free-to-start Basic Rules document, and especially the High Elf which is the only Elf option in the SRD v5.1 and is used as the Elf character in the various Starter Sets (though Wood Elf does appear as a Starter Set character in some niche Starter Set products like STRANGER THINGS Starter Set). Keeping Drow as Paid DLC in this Freemium game is okay on its own; they're a more niche character option. For today's player base, Xanathar is a much more well-known character than Drizzt - because Xanathar headlined his own 5e book and Drizzt has not, and there are more players new to the game with 5e than all previous edition players combined. So Drow doesn't HAVE to be a frontline option. But when combining that with terms like subspecies or even the until-yesterday officially-accepted jargon of "subrace," and combine it with a history of considering Dark Elves as evil by default, you get a swirl of issues that lead to Geneva, we Have a Problem. Major Tom to Ground Control, we've encountered a potentially racist concept in our Player's Handbook, how should we proceed?
We proceed by choosing the most empathetic of options. I'd argue that Ancestry is that one. And you ignore terms like subancestry and pull Wood Elf and High Elf out of the Elf block and include them as full Ancestry Options. and you include "Mixed Ancestry" as a fully moddable toolset in the DMG with a few customized takes on it in the PHB - Human/Elf Hybrid Ancestry and Human/Orc Hybrid Ancestry specifically - with a sidebar saying that all lineages can be customized for hybrid ancestries if you reference Chapter X of the DMG, and these are just the two most common custom hybrid ancestries.
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