Beowulf fought Grendel, who was semi-human ("warped in the shape of a man... bigger than any man"), and Grendel's mother, then a dragon. Odysseus defeated a Cyclops and escaped other monsters, but most of his fighting was against other human warriors. King Arthur fought human warriors, though he crossed paths with hostile magic. Robin Hood had 100% mundane human opposition, so far as I know. Miyamoto Musashi and Connor McCloud (of Highlander) and Jaime Lannister (of Westeros) fought humans, mainly humans with swords. How often do you run stories in which your protagonists fight human (or demi-human, that is, the species which can become PC) with class levels, and how often do they fight "monsters" in the sense of beasts, monstrosities, aberrations and so forth? Are their enemies greedy, ambitious, cruel people, whose goals are unjust... or are their opponents a variety of hungry carnivores?
