Reverse-engineering the Standard Fantasy Races (TM) into primates that exist in the real-world has fourfold purpose: one, stale fantasy tropes are stale and mythologizing the real world is much more fun and meaningful for me. Two, it's the easy go between of "humans only" and "lots of choice of fantasy peoples", since both are true. Third, it allows you to focus on the really weird fantasy species that can be thrown into the world to interact with. Fourth, I have a feeling it's a solid way to circumvent "let's go into the caves and just murder everyone". We have chaos-spawn for that.
Humans - Homo sapiens sapiens - This is us.
Dwarves - Homo sapiens neanderthalensis - A bit shorter, a bit stockier, live up in the lands of ice and snow. Possibly deceptively high-pitched voices.
Elves - Homo sapiens idaltu - Immediate ancestors of humans, now fading out.
Halflings / gnomes - Homo sapiens floresiensis - The little people. Tend to come from small, remote islands.
Orcs - Homo sapiens denisova - Closely related to dwarves, significant cross-pollination between the two peoples. Live in a vast and rugged wilderness, far from civilization.
Ogres - Homo sapiens carnifex - The result of heavy arcane reagent poisoning. Gigantism, mental degradation, violent cannibalistic tendencies.
Tiefling - Homo sapiens cambionis - The result of a cubus transferring sperm between a male and female victim. Sterile, generally mutated.
Aasimar - Homo sapiens nephilli - The result of a angelic siring and miraculous birth. Sterile, generally mutated.
Goblins - Lemurs and tarsiers - Loud, rowdy, huge tribes, downright bizarre looking really.
Hobgoblins - Chimpanzees and bonobos - Tool usage, have figured out war and raiding parties.
Bugbears - Mandrills - Ye gods, look at those teeth.
Firbolgs - Orangutans and gorillas - Eminently chill dwellers of the inner forests.
Trolls - A hunchbacked, ape-like mass of tumors. No one knows what it used to be.
Giants - Gigantopithicus - Huge, rarely seen.