when any person goes out under the stars for a few hours, there is every chance in the world that they will see something that they dont understand.

Men have been sitting around camp fires for millions of years looking up at the stars and noticing that every once in a while something new happens, or something different that they simply do not understand the reason for.

I once saw a trail of a falling star that glowed in the night sky for a long time.
I never saw the falling star itself, but I did see the trail left and it was weird.

Now I can see how had another person seen the same star trail in the sky that i did, and didnt understand what caused it, how ideas such as "An angel fell from heaven" might get started.

The lack of correct information leads our imaginations to invent answers that fit the circumstances.
So a falling chunk of rock into the atmosphere becomes an angel that has been cast out of heaven.
The same inventive mind that came up with the "Falling Angel" idea can also come up with a back-story to support this idea...and soon a whole new myth is being told around the campfires.