Familiars and their ilk

Thinking about all the long lived races in D&D, it makes me wonder why you don't see more of them taking humans and demi humans as familiars. After all they could have class levels to make them a potent threat rather than an xp sinkhole. Also opposable thumbs. Don't underestimate the use of opposable thumbs. Cats don't have them, lizards and bats don't have them, demi humans do. Enough said.

Art from here

LooneyDM out