Yeah, there were studies done that found a human can't reliably throw a rock hard enough to kill even a rabbit from pretty close range. Rocks are blunt and usually only stun the target.

It was the fact that a dozen people all throwing rocks is an unassailable obstacle to any predator or prey. You can corner animals or ward them away. And if you think about it that's always been roughly how human wars have gone: masses of spears, slings, arrows, bolts, bullets, shells, missiles, etc. Our one big trick is a DDoS of violence.