Halfmen

The result of Asmodeus taking pieces out of the Fourth Wall, stripping them of their magic, forcing them into a shape and tossing the leftovers outside, where they commenced to having all the sex and babies. They're pretty good at that. 

The predecessor of humans and halflings, these are the most basic of bipedal creatures. No fangs nor claws to speak of, relatively small and weak, halfmen are endurance hunters that pursue their prey, for the most part. They are good foragers in general, but their lack of natural instinct (as they are not supposed to really exist) means they're prone to trying to eat things they shouldn't. This has resulted in some interesting cuisine, but spent a good few centuries resulting in interesting deaths.

The defining difference began when the halfmen took to sea with the kobolds, and the species began to trend smaller, adapting to a relatively short and fine stature of just small-human.

Humans, on the other hand, benefitted from being taller, denser, and in general bigger. The several centuries they spent apart, going their separate ways made the qualities stick.

A halfman in the PS era is a cross between a halfling and a human. They're generally infertile, I think, and prone to inherent problems like genetic disorders.