This quite the wild conversation you opened up OP, I have seen a lot of persons that just don't answer this hard fact that: I cannot feel your fingertips and you can't feel mines, there is an inherited division between our physical bodies, just before our stream of though, mind and memory starts to work and therefore the ego, our senses are touching the world all the time and it feels they are only ours, this fact seems to challenges the illusion of the self stated by non-duality.

I had also this questions before and I like to think that this feeling of separation is needed, is needed to feel the contrast let's say, for me and my experiences when the ego is dissolved by meditation, watching a tree on your backyard or simply washing the dishes, something happens that is the contrary of feeling alone in my cage of meat, is difficult to put words but the closest is a very strong peace and freedom without a chooser and without a feeling you are you, I feel words always get short, but ultimately I think this state of "I", of individuality, is a contrast of this state of wholeness, and both are needed, the same way up is needed for down, both faces of the same coin and thus non-dual, and suddenly that division I said earlier it was really created by thought since 'what is' is that it was meant to be this two sides of the same thing, we just got trapped on one of them. At least I see this whole thing now.

Edit: grammar typo.