String theory arises from attempts to reconcile contradictions in contemporary physics through the use of mathematics. Specifically, the contradictions that arise when attempting to reconcile theories of gravity governing the world of planets, stars, and galaxies with the workings of the microworld of subatomic particles, governed by quantum theory.
Panpsychism, if I understand it correctly, is an attempt to make sense of the fact that we, and, apparently, some animals, possess consciousness, specifically, self-consciousness. Why this is a problem is rather beyond me. It is easy to see how consciousness has survival value. I'm pretty sure I have laid this out in a response to one of your articles so I won't repeat myself.
In brief, whatever has survival value can be selected for. Mental maps of the world have survival value, and mental maps containing the mapper, that is, consciousness of self, have even greater survival value, and thus can be selected for naturally, therefore, consciousness can arise through evolution by natural selection.
Mother nature does not care if we understand it, or the exact neurological processes by which it works. The only thing of importance for survival is that it works.