Certainly the first true humans were unique by virtue of their large brains. It was because the human brain is so large when compared with that of a chimpanzee that paleontologists for years hunted for a half-ape, half-human skeleton that would provide a fossil link between the human and the ape.
Don't, for goodness' sake, keep on saying 'Don't'; I hear so much of it, and it's monotonous, and makes me tired.