I'd like to take a stab at a non-supernatural theory of consciousness. Consciousness is a simulation. And more exactly the simulation is of social relations, i.e., interactions and possible interactions with other human beings. In other words, consciousness is first a social phenomenon, and second about the physical world.
If nothing else, such an understanding of consciousness explains perceptual illusions. It also explains something Dawkins pointed out as the basis of religion: the tendency of human beings to impute agency to non-social physical events. Why? Consciousness was originally to enable ever closer, more effective social cooperation and organization. As prey species, hominids without the specialized advantages of other animals would need to be able to use the very important resource of other members of the troop.
Accordingly, the connections between consciousness and the physical world, i.e., tools and nature, while important, is secondary.
I suggest also that consciousness as simulation explains why there is the counter-factual subjunctive in language.
There is also a philosophical nicety about it: it sidesteps the metaphysical entrapments of posing the duality of a physical world and of a spiritual/psychic world.
[My three-year old had suddenly decided that she has been ignored long enough and I can't finish now.]