There is an easy conter argument to what you're saying : flat earthers. Poeple are seriously believing that the earth is flat in an era where humans have literaly visited other planets. It's not because poeple have physics and scientific proofs that dragons didn't exist, that they all knew it didn't exist. Humans weren't a unified entity. They weren't an efficient intelligence that used every imediately aveilable information to make good conclusions. They were humans. Coming across such an enormous lizard-like "bone" could a 100% have caused the dragons' myth.