I think with humans it most likely started as a means to survive in environments beyond our natural capacity. From there, it evolved into an almost necessary part of survival in everyday life. I say “almost” because I think some humans would survive without fire or any artificial source of energy. Maybe not.

As far as being pyrophytic, that may technically apply exclusively to plantlife. Although, there have been many times I’ve sat around the campfire, staring into the flames in a vegetative state.