Myths are actually symbolic records of distant past.

Here, as is well attested, in many contexts, 'dragon' meant an army. There is a very simple explanation for that - just as dragons, armies would:

- burn villages
- steal cattle (armies needed cattle as food)
- kidnap women (virgins) as brides
- bring smoke and fire

In one of early medieval chronicles of Poland a Pomeranian army is referred to as a 'fire dragon'.

Also the myth of Wawel Dragon is basically about the change of authority, as the dragon is the old authority. What is interesting is that it has been proven that both Czechs and Persians have an analogous legend - in case of Persians it is the legend of Babilonian Dragon, it's also the same story as in Book of Daniel, but mind you, Poles Czechs and Persians didn't take it from the bible, but all got it from the Scythians.