You claimed the vast majority of people you know are physically unable to kill. I think that is laughably naive.

If you mean that it is harder than you'd imagine to kill someone bareheaded, I also agree. But humans are tool makers and users. A big stick or rock to the back of the head was a common way to die in our distant past. And if you want to not allow any mechanical leverage in the killing, most people are _physically_ capable of pushing someone. That could be off a cliff, down the stairs, or on level ground where someone trips and hits their head.

This isn't a question of morality: it is a matter of physics.