When you identify your existence as being 'the entirety of your present experience', it causes solipsism because when you, 'by analogy', conceive of others, they must too have their own little 'experience orbs/worlds', which may (or may not- according to solipsists), exist 'out there' beyond the bounds of your experience 'somewhere' ('beyond your experience' is not a place) unknowable.

The humans that you then interact in your everyday life, basically become non-player characters, sims people. That may or may not, represent within your experience, the actions of a person acting within their own private 'experience-orb/world'. With some unknown causal correlation occurring between the two 'experience orbs' (the sum of one's present, private experience). Or with nothing at all beyond your world, according to the solipsist.

So what's the solution to this isolation? It is to conceive or identify oneself in a different manner. Your theory of what you are, is almost automatically a theory of others. I cannot help but, 'by analogy', extrapolate the way in which I exist to be roughly the same as the way in which others exist, it is my natural inclination. As in, I don't interact with someone and conceive of their experience is being this amalgamation of 47 different senses I've never experienced. And I don't naturally conceive of others as p-zombies. Why? Because I identifying oneself as one's body, within a public external world.

So we see other people as 'others', because we identify ourselves as being our body, and we identify our visual experience as being a direct realist type 'window upon an already there world'.

But could it not then just be the case that my experience-orb really is just 'ontologically private', it really is completely cut off from everything, or nothing lays beyond, and I've just mentally structured my own experience in such a way as to generate an experience of others. So I have these perceptions and experience, and I mentally identify myself with a particular part of it, or you could say I structure my experience so it is in a particular mode (of say, being this body, within this external public space), which, due to my natural inclination to by analogy mentally place other 'windows upon the world' into the eyes of humans around me, causes my visual field - the world around me - to be experienced as public?

So what came first, your perceptions and the way you structure them mentally (is the space around me public? is it private?), or the public space inhabited by others? Which caused which?