I’m with the camp that proposes that the “Dragon” myths come about from folk finding the remains of mega fauna (giraffes, mammoths, sabre toothed cats) left over from the younger dryas extinction 12,000 bc and the occasional finds of prehistoric crocodiles and dinosaurs that fall out of cliffs.
Miners looking for copper and other ore would have come across them fairly regularly i imagine.
I find that not only quite a reductive argument (the idea of the dragon developed from the discovery of large bones and skulls) but also quite a selective argument (as it misses out many of the distinctive features attributed to dragons).
Large bones, or even encounters living crocodiles and pythons, would not necessitate an explanation of flying creatures that could breathe fire and hoard gold, for example.
There is no single universal idea of a dragon. At one end of the mythological spectrum there are "giant worms" that are essentially big hungry snakes, and at the extreme far end there are Chinese dragons with their mystical significance. In between, there are all varieties, and our modern perception is no doubt coloured by many comparatively recent fictional portrayals, ranging from Smaug to Puff to the seemingly endless series of Anne McCaffrey books, and the examples given in D&D handbooks.
Human imagination works by combining and exaggerating ideas:
Tim: I saw a crocodile on 'oliday. It were 20 foot long if it were an inch.
Marty: Twenty foot? That's nothing. My mate had a pet one. It were 40 foot long. And that were just its tail.
John: Never mind that; I knew a bloke who 'ad one that could fly.
Graham: Fly? That's nothing. When I were a lad, dragons could breathe fire. You don't get dragons like that these days.
Marty: Breathing fire? Luxury. You don't know thee were born. We had to cope with dragons that had ineffable ancient wisdom.
Tim: Wisdom be damned. Ours had 'oards of gold. 'Oards of it, ah tell thee.
Anne: Well, the ones I heard about could form a deep spiritual bond with their riders, and they hung like bats in huge caves until they were needed to destroy the threads...
All: Oh, ferchrissakes...
I am sure that the inspiration for dragons was a combination of things including to a greater or lesser degree:
Fossil bones
Travellers' tales of crocodiles, cobras and pythons etc.
Whirlwinds, waterspouts, lightning strikes.
Caves in volcanic areas. Volcanic vents, etc.
Tales to scare the children.
Metaphorical references to armies, individual warriors, banners, ships, etc.
Attempts to explain everything from the weather to the failure of the crops.
The love of a good story.