I don't consider it to be one unified story at all, I mean some of the series obviously are connected, but the rest are, as the name suggests, legends about Zelda. Unconnected unreliable narrations about some sort of heroic past events. Everybody agrees about the characters involved but as to what exactly happened, that is lost to time. So each culture is now telling the story a different way, emphasizing whatever is important to them.

I consider as a sort of modern equivalent to the coyote stories. or Paul Bunyan, Finn McCool, Gilgamesh, Or really, any legendary heroic epic passed along by oral storytelling.

So it is fun to try to fit it into some sort of unified timeline. But I don't think it is, that is not how they were actually written and we would loose most of the interesting storytelling flexibility if that is how they write them in the future.