The art is almost exclusively of animals, including bison, deer, horses, wooly rhinos, and other species. Humans are rarely seen in cave paintings. The scenes involving humans are often depictions of hunting strategies.
The animals are very well-drawn, showing skilled design and observation of proportion, while the humans look like stick figures. This may be because the art was for instructional purposes. Before a youth's first hunt, perhaps he was educated in, first and foremost, what the animal looked like, and then maybe how many of that animal could be found in a herd, and so on. Prehistoric painting may have been a matter of necessity for survival, to teach others how to hunt for themselves and for the group. A step further from education, and these works could have been religious or superstitious in nature—perhaps these people believed drawing a lifelike picture of an animal captured the animal's spirit (an idea still found in some indigenous cultures around the world). Perhaps this was some magic ritual purported to bring good luck on the hunt before leaving the cave. It is not a stretch to imagine some of these cultures could have worshipped these animals (animal idolatry is prevalently described in the Old Testament). The artwork could have been sacred, since it was separated from the other living areas in the caves. Plus, mankind at this time hadn't nearly the amount of leisure time and luxury that we have today, so it is unlikely that people would make art purely for aesthetic ends. These paintings were somehow a part of their survival, of their way of life.