Lorry art of a dragon slayer, Jaffna.
To me, dragons make perfect sense. They’re dinosaurs. If I found a T-Rex skull, as proto-humans must have, it would look like a dragon to me. Awesome attracts awesome. If I didn’t imagine that this thing also flew and breathed fire, the next village certainly would. I mean, how do we know dinosaurs didn’t breathe fire anyways? Un-burnt dentition I guess, but still.
Sadly, this idea has been taken up by Creationists to support their idea that the earth is about 10,000 years old, and that dinosaurs and humans coexisted. I still think it’s plausible, but not taken to that non-sequitur of an extreme. It’s quite possible that people saw dinosaur bones and communicated them as tales of dragons. Perhaps knights even brought some teeth home.
Here’s another theory:
Jones argues that the image of the dragon is composed of the salient body parts of three predator species that hunted and killed our tree-dwelling African primate ancestors for about sixty million years. The three predators are the leopard, the python, and the eagle.
Because the image combined features from three dominant predators, it could quickly send the neural message very dangerous animal. (The Evolution Of Monsters: Salon)
I somehow find this far less plausible.