Well, in my current lore (which doesn't have to be set in stone) elves are descended from Fae and humans mixing together. Having a pixie race is do-able but how would we explain their existence?
Maybe a Fae made something that resembles their most generic forms (although Ashlan the lion is probably also a Fae) as some kind of game? Ultimately, whether a race goes in depends on a few factors.
1. Can we come up with good lore for it, or is it a staple that people expect (like humans, elves and dwarves).
2. Can we invent good racial abilities for them and make their unique stats fit into the game well. This will be easier to understand once the combat system is more fleshed out because then people could better appreciate what the stats and so-on actually do.
3. Is it sufficiently different from other races. One reason I haven't accepted some otherwise decent race suggestions, like lizardmen, is because they sort of fall into the category of Otherkin, which is already being used to provide for everyone's favorite animal races. But I'm not sure we can fit every animal in without it getting silly, or having no significance from a game mechanics perspective. I don't want races whose only difference is ultimately in their description, I'd like different races to play somewhat uniquely from each other