"In those days the serpent went upright like a man, nor was he exactly nonhuman in shape, but his beauty was a different from a man's as day is from night. He was lithe and gorgeously scaled and by standards a supremely handsome, supremely male creature."
- C.L. Moore, "Fruit of Knowledge"
In my post on the demi-humans of the pre-Flood world. I forgot the Serpents. As you may recall from the temptation of Eve in the Book of Genesis, Serpents had limbs and come talk Sounds like a Howardian Serpent Man to me.
Getting cursed by God and loosing his limbs suggests (to me at least) variable levels of snake-ness among later serpent descendants--something like the Yuan-ti. Conflation with the Snake Men of Masters of the Universe is done at your own discretion.