I view "being a person" as a lot like gender, in that it is absolutely something that is personally and socially real, but it is nowhere near as easily defined or biologically determined as people think, and actually exists upon a sort of spectrum or continuum of experience.
To be clear, I'm not talking about personhood. I think any informational system that possesses the qualities of sapience, which includes, without exception, all human brains, and will eventually include extraterrestrial and artificially created examples, possesses personhood and the inherent dignity of a person. I'm speaking specifically about being a person as in possessing a single, consciously appraised identity construct. I think that idea is a lot more fraught than people realize, but we're just conditioned never to contemplate whether "one brain=one person" is a faulty heuristic, even though it obviously must be, since the brain is hardware, the mind is an operating system, and the self is an interpretive framework applied by a mind.
Like, in reality any mind, brain, and even the idea of a body is a massively emergent system of multiple repeating phenomena at multiple levels, you know? And brains neurologically function in a naturally distributed and parallel manner, as you can see clearly by things like the split brained experiments or how often people that consider themselves singular will talk of being internally divided, arguing with themselves, or being of two minds about something. Like, a brain first functions as multiple informational structures running within its mind system, and then collates the experience of those according to the framework of being one. Plurality is literally just experiencing a personhood not defined by the successful maintenence of the expected illusion of being a singular person. And not maintaining that illusion is morally neutral to me to be clear.
I do also think that since the mind is an intangible informational structure emergent from the brain, but not synonymous with it, one brain can absolutely support multiple minds with barriers between them as well, that run in parallel on the same hardware, although the overlap of space would make it difficult for them to be entirely separate.
I think in general a true understanding of plurality takes a reevaluation and deconstruction of the self as something that exists primarily as a construct of the mind to interpret human experience.
If you want an insanely dense and complicated read about this kind of thing I recommend the works of Douglas Hofstader. Oh, and I'd also recommend the Dueling Neurosurgeons as a good introduction to a lot of ideas in neuroscience that can really get you thinking about this kind of stuff.
Anyway that's what I wanted to say. The self is an illusion and if you reframe it on a philosophical, psychological, and neurological level of understanding, you will have an easier time explaining plurality as part of the natural continuum of human nature and modalities of being.
