David’s comment: The brain became bigger and more complex. That is true. How about recognizing that God did it on this planet and nowhere else?
dhw: I don’t know if the complexification of the brain triggered the enhanced awareness or resulted from it.
David: Not a chicken and egg problem. To me we are given a big brain and learn to use it. In our ancestor fossils, brains jump from one size to another with no itty-bitty steps.

dhw: What part of “we” decides and learns to use it?

My brain is part of me and I feel I am inside my body. H. habilis probably had the same feelings and used his newly developed brain to develop new thoughts and concepts.