Dragons are a fictional-ish type of winged mammal that lays eggs. They tend to be big, but their depiction varies per story and per author (and per geographic location). The first dragons were really weird and it wasn’t until maybe halfway through the Middle Ages that their image was cemented as lizard-like with wings.
Asian Dragons will have their own page, since I think of them as separate.
Dragons existed for sure.
More to be written later.
I think people should not be as harsh on medieval and ancient peoples for believing in dragons. One theory as to the origin of mythological dragons are…well, dinosaur fossils. As far as people back then may have believed, dinosaurs were dragons.
In fact, it’s perhaps one of the greatest tragedies of history (alongside the invention of mouthwash) that we didn’t just call them dragons.