Perhaps it would facilitate understanding to use the word "mythic" instead.
Meaning that a story can be 100% true and still carry nuances, ramifications
and impact on the human psyche that give it the force of myth,
but with the certainty of fact.
Very well put!
I'm trying to think of good examples from history (apart from the Greatest Story Ever Told, of course).
I guess the story of the Titanic has true mythic qualities. It really happened, and it impacts our thoughts and memes even today. How would we refer to futile activity if it wasn't for the Deckchairs on the Titanic?
Also: there are so many stories from war with true mythic qualities. The seige of Malta. The battle of Iwo-Jima. The Battle of Britain from a UK perspective, or Stalingrad from a Russian one.
These stories aren't just dusty history: they live in us as models of defiance, resistance, self-sacrifice, and of course sheer bloody terror. These are profoundly spiritual things.