MUAHAHAHA!

We are TOLD that history is like a slate that cannot be rewritten. And we are TOLD this by the most knowledgeable mortal on the subject in Eorzea.

BUT mortals can be wrong about the nature of the universe, as was Aristotle following an era where his perspective was considered irrefutable.
You also have an unusually strong strain of the Echo. And being the main character, you are wont to... bend the perceived laws. To quote Lightning, "We make the impossible possible" in true FF-fashion. If anyone is going to break the rules, it'll be you.