A good indicator that someone is telling the truth is when multiple witnesses tell the same story, with similar details, especially when they have no opportunities to collude. This is the case with dragon legends. Dragon legends exist in virtually every culture worldwide, spanning across entire continents, diminishing the likelihood of corroboration because entire oceans separated them. These legends not only bear similarities to each other, but also to animals we now know existed in reality: Dinosaurs.
This poses a threat to Evolution. If it can be proven that dinosaurs died out only thousands, not millions of years ago, the entire Evolutionary fairy tale would come crashing down (not that Evolutionists would admit that, as history shows they are highly resistant to contrary evidence).
One Evolutionist who recognised this problem was Carl Sagan. And much like Creationists, he understood that dragon legends are most likely exaggerated stories of dinosaurs. But Sagan's imaginative explanation is, put simply, bonkers. Sagan believed that while no human ever saw a live dinosaur, our ancestors did. (1) Obviously, a magnificent reptile is going to be very terrifying to a tiny little rodent, so Sagan concluded that these creatures were so terrifying that the memory of them actually got passed down throughout the generations. Man finally appeared on the scene and inherited these memories, so when they lay down to sleep at night, they would dream about the dinosaurs that their ancestors saw, and wake up and tell about their dreams.
Does this sound realistic to you? I can tell you this much: Sagan performed exactly 0 scientific experiments to prove his strange idea. Memories can't get passed down. A far more realistic explanation is that the Bible is true. Dinosaurs and man co-existed, and people wrote about them as dragons.
References
1. Sagan, Carl - The Dragons of Eden, July 1 1992