Exactly what is it you want to know? What makes us different from animals, or what?
In my opinion, what it means to be human is different from why we are humans or why we're different.
If you want the answer to be what it means to be human is that we - unlike other animals - are responsible for our own actions because we're (albeit arguably) smarter than other animals and are capable of reason. As such, we need to take responsibility for our own actions.
Emotions have no place in what it means to be human, as it's not a unique human attribute. Other animals have emotions too, so emotions isn't what humanity is about. Spirituality, on the other hand, is something uniquely human and - I believe - stems from our curiosity and desire to understand the world around us. I also believe we're the only species capable of reason and logical thinking, which leads to philosophy. So those two are certainly uniquely human traits; unlike emotions which is really only a chemical response in our brain.
I think the strongest argument you can bring to the table about humanity is that we're possibly the only species able to ask that question.