Since this particular painting is so massive I would conclude that it was done by more than one person. Possibly people that lived in the caves at the time of the paintings. Maybe it was by people that settled in the area for ritual or sacrificial use. Another theory of mine is that a shaman, chief, or some kind of medicine man had these paintings in a place that was of religious value to them. Being that it is inside a cave it was secluded enough for them to have their privacy. I think they painted animals because they were an important part of their survival. They depended on these animals for their furs and meat.. The meat they received from hunting these animals was probably their main source of food, and the furs helped keep them warm. Without it they would have struggled to survive. Perhaps they painted the animals to show their appreciation to them. They probably did rituals and sacrifices so their gods would keep the animals