Prehistoric humans believed that animals had intelligence and that they allowed themselves to be killed. To make them more willing to die, they would go through a pre-hunting ritual. The hunters, mostly males, would go deep into a cave. There they would use paints made out of local plants to draw life-like and mature art in the caves where they lived. The scenes generally depicted humans hunting and killing game animals, and of those same animals re-emerging from the earth to renew their life cycles.
What we think is that the paintings and the ceremony they were a part of were a thank you for their generosity and a plea to the animals they hunted to continue sacrificing themselves. These paintings were in some ways superior to their modern equivalents, which was probably a testament to how important the animals' continued sacrifices were to the hunters..