Going by the presidence set in the series so far, I have a really hard time accepting that the writers would take it to such a metaphysical level (although I wouldn't be upset if they did). Audiences generally roll their eyes and get upset when literal plots end up becoming amorphous metaphysical new-age explanations. Modern audiences are only satisfied by the physical and physical explanations, and anything else pisses them off.
If you study the timelines mentioned in the series, what is very likely is this:
The humans had a huge conflict sometime in our future, and some managed to escape it. The humans are originally FROM Earth. The humans that escaped found Kobol, and lived there for a 2-4 thousand years. At some point, the thirteenth tribe decided to go back to Earth, and about 1,000 years after that, the colonies on Kobol all went to their respective planets and left kobol. Pythia recorded the 13th tribe's exodus back to Earth, that's how the humans now know about it.
So the humans main goal is to reunite with the 13th tribe, and they believe they are on Earth. What's unclear is why the cylons felt the need to go to Earth, and why the final five supposedly know the way to Earth.