This sounds eerily similar to some of the early proofs of God. I think there may be a flaw in this line of thinking.

|Thus humans can never understand the brain because the brain has equal complexity to itself and for the brain to understand the brain then it must have greater complexity than itself which is impossible.

We don't need to know the entire state of the brain at any given moment to understand the mechanics of the brain, just as we don't need to know the entire state of every molecule on planet Earth in order to understand it's physics.