Humans take a much much longer time to evolve than bacteria (and much longer than we've been shooting each other), and your average human doesn't die to gunfire

Humans take a much much longer time to evolve than bacteria (and much longer than we've been shooting each other), and your average human doesn't die to gunfire before they get to reproduce. I'm sure if you put humans in an environment with a major chance of dying to gunfire before they reproduced for hundreds of millions of years or whatever we'd start to develop thicker bones or something - or just earlier and faster reproduction.