Self is not a thing, it is a process.
It is the sum of my beliefs about myself. Both within my awareness and outside of it. Beliefs are also a process.
Some of these beliefs are held in my body rather than my mind.
The beginnings of this belief making, or meaning making, go back at least to the time of there being only single celled organisms.
The self is a process the physical body has "developed" through evolution to aid in the preservation of the organism. A meaning machine. Able to thrive adaptively in any environment.
My two cents....
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Ever onwards and upwards!