Most of weird European and Middle Eastern legends and fairy tales originate from drugs or encountering real artifacts or phenomenons which they couldn't explain. Look up how cyclops appeared in mythology.
Well, eastern dragons always reminded me more of a giant oarfish. And some central europe dragons weren't that far off, being described as flying snakes.
I think "every culture has a dragon" is kinda misleading.
"Every culture has a creature that got translated as a dragon" seems closer to the truth. The creatures themselves have a great variety between them.