How man invented fire?

Answer 1

I am going to be picky here and say man did not invent it, he discovered it.

There was plenty of natural fires around him, due to things like lightning, he simply discovered the joy of it's warmth, it's ability to keep predators away and the way it cooks meat.

For the longest of times man did not create fire for himself, he would instead keep fires going for ever and ever, using lit branches to move the fire to new places.

Eventually, one clever man or woman must've realized the relation between fire and heat, and learned that with enough heat, they could create new fire.