If one were to look at traditional (real world mythological) races, one finds...
...and that's about it.
*blink blink* Just what do you mean by "real world" here? Traditional role-playing games surely, not real-world mythology. Because there's a hell of a lot more mythological races than that.
Satyre, Dryad, White Women, Centaurs, Mermaids, Nixies, Selkies, Trolls, Phooka, Folletti, redcaps, Spriggans, boggarts, Clurichaun, Domovoi, Vodyanoy, Rusalka, Vila, Kappa, Kitsune,Tengu, Apsara, Aziza, Tanuki, Mimi, Tjilpa, Caipora, Duende, Chitauli, Rokurokubi....and that's just a start
. There's thousands more supernatural races in world mythology.
Even if you do the dodgy thing of combining different mythological creatures by shared characteristics, there's a hell of a lot of diversity in European mythologies, much less the rest of the world.
This sounds to me like a dodgy attempt to support a limited creature selection in rpgs, rather than anything based on actual mythology.