You bring up a couple of ideas here....

First, I don't even feel that anyone should accept what I write as true, because it is not their own realization. My purpose in all my writings is to guide people to their own personal enquiry if this is what they are driven to do. Ideas and beliefs have nothing to do with knowing what we are beyond the facade of the self.

Next, regarding the thought experiment about the teddy bear... We are speaking of a different matter, because this has nothing at all to do with defining the sense of self or seeing what is beyond it. Nor does it have to do with the clarity of the mind. It is a practical matter, which is quite different. But what you call birth memories is a psychological matter, or what some may call a spiritual matter, and it has to do with one's personal life experience that determines their feelings, emotions, traumas, relationships, etc.

What you noted about the physical world is also applicable to alternate realities in my experience, because the sense of self is retained as well as senses, though the senses may not be physical. In my experience there is a silent stillness out of which everything, including consciousness, arises. And thought and creation is produced by consciousness in conjunction with the natural elements. Therefore, all that appears to exist, whether physical or not, has to do with the phenomena of manifestation even though people are wont to differentiate it into something different, special, nonphysical, and so on.