You have to walk… barefoot. My feet are messed up and I have some impressive callouses on the balls of my feet. They are a little better after surgery, but recovery sucked. Ultimately, your feet build up protection. Caking on mud probably helped. Animal skins, rudimentary sandals from various plants, and other natural resources could provide extra protection. Unfortunately, we have built an environment made for shoes and evolution is doing the rest. Walking on pavement is not great without shoes. Especially when it bakes. Walking on soil and grass feels a lot better.