An elf goes to a human hospital and the doctors are like holy fuck. You broke our blood typing machine.

“Sir, the results are in, and technically you are a fungus.”

Elves evolving from either a cat-like species or a squirrel-like species makes the most sense to me. Everything about them suggests that, like humans coming from apes, elves also came from arboreal roots. But unlike proto-humans, which were diurnal persistence hunters, elves’ ancestors are likely nocturnal, agility focused, and also not at the top of their food chain. While probably omnivorous, their larger, wide-set eyes and larger ears suggest that they had to have a greater awareness of predators than humans. (Which does give me the extremely satisfying mental image of long elf ears twitching and turning like cat ears at the slightest sound.) Their ability to basically not sleep also suggests a heritage of needing to be constantly alert to danger. The longer life span and lower birth rate might also be indicative of it being much riskier to stop and reproduce more frequently, requiring an extremely well-defended home before young proto-elves were worth the risk to the group.

Point is, there’s decent evidence to suggest that the most elves have in common with humans is that they’re mammals, and otherwise evolved from completely different types of creatures suited to a wildly different ecological niche. You couldn’t get a blood transfusion from an elf anymore than you could from a raccoon. The fact that elf-human hybrids exist probably has more to do with wonky magic shit than anything biological.

so… elves and humans are like hares and rabbits? similar shape, you’d think they’re closely related but NOPE