ok a few things you said that we are perfect for reproduction, that is a 100% false statement. numerous children are aborted naturally aka miscarriage also every child is born premature because the birth canal has not caught up with us and if we were to be born when 100% mature then we couldnt come out without a c-section
some our predecessors were born with enlarged jaws with flat teeth because and ridges on the top of their skulls which indicates that they were probably primarily if not entirely vegetarian their are fossils to back that up. that is the only example that i can come up with off the top of my head but there are several predecessors to our current form.