A tree knows it’s a tree implicitly, a dog knows she’s a dog, a rock is a rock implicitly -- it would never question its ‘rock-ness.’ So too, humans know how to be fully human.
Socrates said that it was man’s virtue that made him fully human, the ability to know right from wrong. Later philosophers expounded on that idea and reason became the distinction that defined her full humanity.
Although virtue and reason certainly separate us from other species, what embraces our full human-ness, I think, is the ability to recognize our spirit to recognize our divine nature.
That we possess spirit is implicit. That we know we possess spirit is what’s distinctive.