That's begging the question. We don't need to look "at every kind of mythological creature that gets classified as such nowadays" from "cultures that wouldn't have recognized the concept".

One could stick on those classified as such in western culture - which is where the fantasy novel about dragons and knights and spells and the rest are based on.

And in there, dragons have quite specific characteristic and vibes, as evidenced from medieval iconography of St George to countless fantasy book covers and illustrations.