Your general point is well-taken, that the brain bears obvious evidence of careful design. Your example is inapt: there was nothing chaotic about the Cosmic Creation Event. Indeed, scientists studying it determined it was so exquisitely crafted and fine-tuned, to better than one part in 10120, that it is the strongest known evidence for the existence of an intelligent Creator.
Agree about the intelligent Creator.
Disagree about the hypothesis of a big bang.