To corroborate what Araciel says, Faerun is perhaps the most fleshed-out D&D universe in existence. They have trees named in Waterdeep, to give you the level of the detail that's in it. Making new races is nice and all, and I'm pretty sure Faerun has some kind of race that fits the ones you made, but adding it would make it someplace other than Faerun, which is the essense of what Baldur's Gate is, a Faerun-centric game.