No, but ive also never heard about sane people biting the face off crackheads. That doesnt mean crackheads possess some superhuman fighting ability, or that normal people couldnt bite the face off crackheads.

Are the lack of stories of humans killing chimps in unarmed combat because they couldn’t, or because thats just not something normal humans do?

Recall hearing a zookeeper on a podcast a while back mention he was once attacked by an adolescent chimp and he “beat it” enough for it to stop trying to attack him. But #1 who knows if thats true and #2 even if so it was claimed to be an adolescent

Entirely possible lol this is outside my area of expertise so i dont know shit. But it raises an interesting question, above average sized chimp versus someone like francis ngannou or mike tyson. I have a real tough time giving the definitive advantage to the chimp.

Are their skulls vastly more resistant to impacts than ours?

Not a zoologist, but that sounds wrong. A quick google search shows a chimp is about 1.5 times as strong as human of similar bodyweight. An adult male chimp ranges from 90-130 pounds.

Running with the high end, that means equivalent strength of a 195 pound human. That’s about how much i weigh standing at 6’2. Mind you, we ran with the high end for a chimp. They trade several feet in reach advantage for a dangerous bite. I think i could totally knock a chimp out with a head kick before it could bite me 🤷‍♂️