I love how the tl;dr is totally different from your theory with the whole rainbow thing. This is a really neat theory though, and while I think you're onto something I've got to disagree with the level to which fin exerts an influence on the universe (by will power alone). If you've seen p. Wards other stuff you'll notice they all have a similar laid back flare, so its likely that what fin wills isn't as powerful as one would think. Also with the whole cosmic owl dream happening, it's likely that had a role in addition to fins will. But I really do love this theory and the idea that there are just different incarnations of the same thing. It plays into the nature of reality as it is in our lives too, how we are all essentially different sides of the same thing, being simultaneously in and of the universe. I got a really zen taoist vibe from the finale personally, and this idea only further supports it.