Hi Jochen, lots of interesting argument in your essay. I like your "Models are at the heart of our engagement with the world. When we think about a tree, there is no tree present in our thoughts; rather, we use a mental model in order to draw valid conclusions about the actual physical system." Though the conclusions are not always valid, they can be in error. Though sufficiently accurate, enough of the time, for the purposes of our biology
Max Tegmark has said that consciousness is "what information processing feels like from the inside,"(2014) "Consciousness as a state of matter." I'd say in that the visual qualia are, in nature, inseparable from the information processing AND not by themselves the information processing. I have called visual qualia produced form observation 'visual products'.
Re. your "We see something like this moment repeated within small children: up to about the age of 20-24 months, they do not seem to conceive of themselves as separate entities within the world, for instance failing to recognize themselves in the mirror." My personal experience is of being self aware at birth, and aware of my individuality and separateness from my surroundings, others in the room; and very aware of the difference (among those others) between mother and not mother.
With regard to the mirror test: I know it is a standard test of self awareness but I think the reasoning behind it is flawed. The internal experience of I is very different from recognition of external appearance. The delay in recognition is due to not identifying as me, an image seen at a place separate from the physical body, that is not identical to the internal experience of the self, and for which there is not an internal model of that as self, or stored memory to refer to for recognition. The neural pathways have to develop that are necessary for assuming the external view of me perspective.
IE the association of internally experienced I (and the internal awareness of a body associated with that) with an image seen separate from it. In much the same way as a computer game player must learn to identify with the avatar. That is a separate ability from knowing from an internal perspective that one is separate from the external reality. Those animals able to recognize themselves in a mirror have the capability of identifying with an image separate from their own body as if it is them-self, whereas other animals lack the mental capacity for that abstraction, rather than, I would say, not having a concept or feeling of I. 'I' seems to me to have a fundamental, homeostatic, basic survival and reproductive function. Information about internal and external conditions being related to the concept of I. I am cold, I am well fed, etc.
I would say the external reality itself, as it is, can not be known by a human, from the universe centred rather than literal human centred perspective. We do not have the capacity to experience all viewpoints simultaneously. However the external universe can still be the source of our partial knowing and partial understanding through our internal and external modelling
I have found a lot I can relate to in your essay. Kind regards Georgina