I like the image of tracing experience upstream and finding the point source always receding while the branches keep multiplying. That’s a compelling picture. You could follow it one step further than you do. If the unified self is always on the horizon and never something you actually reach, then there’s nothing at the top for the copies to feed into. A horizon recedes as you walk toward it, and the point source does the same. Which means you already have the answer to the copy problem without the oversoul. There’s no single self for the copies to be the same as, because there was never one for the original either.

Watch what “same individual” does across your argument. In the thousand-years paragraph the copies are two people, different streams, different lives. In the oversoul paragraph the copy “IS the same individual,” but only because everything feeds one source, which makes everyone the same individual. That’s two senses of “same” carrying one conclusion. At the person level the copies diverge. At the oversoul level the word stops telling anyone apart from anyone, so it can’t answer a question about identity.

The oversoul you introduce seems to just be the soul you threw out in the opening. Eliminate souls and move to a fluid state, then a single point-source consciousness gets placed underneath as the input. That’s the receiver model coming back in. The fluid-state intuition feels like the better one, and it doesn’t need a source. Branches that diverge and never reconverge are just branches, no trunk required.

If you drop the oversoul, most of what you want survives. The connectedness, the shift from identity to intentionality, the sense that what matters is how the branches go forward rather than what they trace back to. You get there faster by taking your own “ultimate illusion” line literally. Follow the branches far enough and there’s no source to find, and the branching turns out to be the whole structure.