Importantly, the super position doesn’t contain a portion for ‘the observer measures both outcomes at the same time’, so there’s no way for us to see all superposition’s at once.
I feel like here you’re just moving the goal post again, if you’ll excuse the expression :)
Even if there is no superposition in which an observer sees both outcomes, there must be some point in space and/or time that decides which of the two superpositions we see. Whether that is in the experiment, in the brain or in consciousness or whatever. I mean we only see one superposition, so there must be something that “decides” (randomly as far as we know) which one it is. And that decision is a kind of collapse of the wave function, no?
I am not a physicist though so this is just me rambling from my limited understanding.