There's not much evidence that Jesus returned from the dead.Paul Revere didn't shout "The British are coming!" (or make it to Concord)
Coca Cola didn't turn Santa red.
Diana Ross didn't discover the Jackson 5
eBay wasn't founded to help Pierre Omidyar's wife trade Pez Candy Dispensers.
The history of almost every social group embraces a touch of embellishment, a sprinkle of utopian motivations, or a barely concealed lie.
Most of these founding myths, regardless of their veracity, are useful tools to bring members closer together. Most founding myths were introduced years after the incident.
A good founding story has 1 or more people creating something different with the specific goal of changing the world. The lesson here is that if your community doesn't have a good origin story yet (and most don't) you still have plenty of time to create one.