Thanks for the wonderful commentary Julian, makes it worth writing if I can trigger someone to have a conversation.
I mostly subscribe to your view, as an atheist and materialist. There is a key assumption you make which is that there is some common consciousness that we branch from. While this view is supported by Vedanta and Buddhism, and enables reincarnation, it is flatly rejected by the “emergence” view.
If our first person experience is just a product of information integration (Search: “IIT consciousness”) then there is no fundamental connection or field required. Consciousness just emerges from information as a useful byproduct, and enables “substrate independence” with machines and software capable of our kind of experience.
I’m between these views myself, starting from the latter but studying the former. Will we ever prove one over the other? I think we have a chance at testing the latter soon with Neuralink and A.I. research.