He stole it from the gods, defying Zeus's orders and bringing it to humanity. This act of defiance was seen as an act of compassion and a way of improving the lives of humans, giving them a powerful tool for warmth, cooking, and technology.
While fire was the most famous gift, Prometheus also attributed other qualities to humans, like the ability to think and reason, create tools, and build civilizations. He was seen as a champion of humanity and a symbol of knowledge and progress.