Read, “Didi” by Amber Caron reprinted on the Electric Literature website as “A Teenage Girl is a Funhouse Mirror,” and I liked it quite a bit. I thought I’d reference it here because I can imagine referring to it again in the future.
The key takeaway that I took from it is that it is a dramatic rendering of how there is:
- a self that we present to others
- a self that is perceived by others
- a nominally real self, the self that persists across time and has continuity of preferences and choices
But, none of these selves are real. They are figments of circumstance.
cafebedouin.org 
The self is quite a complicated matter, interpreted myriad ways depending on many perspectives. It is also no one thing but multifaceted and ever changing, as you point out above. However, to call it fictitious, unreal, or a figment rather misses the point, even for those parts that are projections and/or misinterpretations. Something very real, foundational is going on with the experience and perception of self that can’t be waived away with the conclusion that it’s all some sort of self-delusion.
My opinion is that culture still lacks a framework to understand the phenomenon well, but mine is that the self is an ongoing transformation or flow like fire or wind or a river or even time. There is no way to fix it into permanence as if that would make it tangible.
I guess the part I have trouble with is: which part is the self? The fact that we can impartially observe thoughts, say during meditation, suggests that we are not our thoughts. And, if we think about the observer of thoughts, who is that? Is it there when we aren’t noticing thoughts? Does it have continuity, from one moment to the next, one year to the next? And, thinking on those problems a bit, the cleanest answer is that maybe there is no one there. Maybe, when you strip down the performance down to the absolute minimum, the whole thing just disappears, a rabbit in a hat, a mirage. Maybe we are all like ChatGPT, just doing pattern matching on the next word or phrase, and in the end, there’s nothing there.
This strikes me as a variety of philosophical skepticism, where we doubt everything, even that we exist. I didn’t like it when I first heard it, but it seems like the most likely answer, now that I’ve spent a long time thinking on it.
Giant topic, but I’ll be brief. The self may be multifaceted and constantly in flux but cannot be separated into discrete parts in search of a core self. That’s IMO the wrong way to conceptualize it. For instance, one can’t really step outside oneself to obtain objectivity but the self is indeed constantly reflected back to oneself as a potential object of contemplation. That’s self-awareness, an example of recursion that presents an obvious paradox. If one peers too far down that hall of mirrors, it’s possible to conclude that there’s no there there, that the self doesn’t exist (which in a material sense it doesn’t). This is also known as nonduality, which might be attempt to merge subject/object and resolve the paradox or more simply to transcend normal modes of cognition.