Because the way it was painted lead to several interpretations.
Explanation:
In this artwork, we have the Bison and a Man, probably injured (the man is depicted laying on the ground). But the way how this painting was executed created several personal interpretations such as:
Who injured the man? The Rhinoceros or the Bison?
Is that a man or a voodoo doll? Because it's known that the primitive man believed that if an animal or object was transported to drawing, everything that eventually happens to the drawing, will happen to the animal. And the voodoo doll is a protection artifact, maybe.
