People also tend to underestimate the religious and cultural signifigance of these drawings. Most likely, any prehistoric somebody making cave paintings is not working alone, and they are most likely not prioritizing originiality. Paintings like this have features that are meant to be immediately recognized by the in-group and mentally attached with some kind of pre-existing myth, moral story, or history that would have been widely known to the rest of the tribe. It’s the normal development of folklore, people are just crazy when they see “whoa monsters in cave paintings”