Earlier quoted context omitted.
"Muddle-headed confusion" is harsh. I'd prefer something like "human intuition not being particularly reliable on questions it wasn't evolved for". If preserving a sense of profound mystery is your goal then... honestly, that mindset is sufficiently alien to me that I can't really think of anything useful to say on the subject. I can understand and share it as an aesthetic choice - mysteries are cool! - but not as a…
Maybe "Why am I I?" is an expression of dissatisfaction at being trapped in the prison of the self. That I only get to experience my experiences, and not other people's. Maybe the answer to the question then is not a proposition, but a liberation from that prison. If one is a religious believer, one might hope for that liberation after death. If one is a transhumanist (which is maybe just a different sort of religion…
We know that a human being can survive with large portions of their brain missing. Entire hemispheres in fact. You understand what it is to be the amalgamation of experiences from both hemispheres, but the hemispheres don't understand what it is to be that experience, they only know the experience of being a hemisphere.