To be human is a burden. We do this thing called thinking. (Some of us assume other creatures and plants don't "think"...more on this later.) So, instead of just responding or reacting, we pause, we complicate. This is actually what I call the "analytics of survival." I have come to concur with those who propose that everything, every move, every action, even every thought by a human is to either consciously or sub-consciously dominate or avoid dominance of their immediate environment, including actions against or with other humans. What makes these "everythings" so complicated and sometimes so shrouded in multiple sequences of actions is...yes, thinking, analytics. Humans run the possible consequences of outcomes and take actions.
So what? Thinking therefore is this ephemeral process, our analysis of survival. Unfortunately human-future appears to me, that short of some form of enlightenment, some intention of contribution and action larger than self, we are on a path of destruction due to a finite food, air, and water supply.
So, in my book of "Understanding Human Nature for Idiots," the definition would simply be Human, n., A biological creature with relatively advanced mental attitude capacities that harbor a brutal, fatalistic inclination to re-create itself at all costs.