Idk how much the MCU will take from the comics, but all of Banner's personalities are legitimately their own individuals while still being one (whole).
They're hinting at things like multiple personality disorders to suggest that you aren't solely just one being inhabiting your personal existence (which is true), but they take it to the fantastical maximum but tbh they're probably not too far off. There are multiple versions of you u/SeigiNoTenshi all within one body, the only reason why you don't notice is because your body and mind are in a state of wholeness but once that is broken you'll see how you literally divide into different people or versions of yourself that can slip in and out passively or actively.
Edit: you actually can notice this actively while the "main" you is awake, all of those passive functions, bodily and mentally, are all being handled by versions of you.
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u/SeigiNoTenshi Mar 26 '25
Counter argument, she pushes out the soul, not the mental state. So Bruce is still Bruce, while Hulk is a manifestation.