There are a number of things that make us human. I would say that there are two main aspects to our humanity.
First, there is our ability to engage in rational thought. Other animals can perhaps think in some basic ways. However, they cannot think in the complex ways that we can. This is one of the most important parts of our humanity.
Second, there is our awareness of the ideas of right and wrong. If you are so inclined, you could say that it is the fact that we have souls. There are no other animals that, as far as we can determine, are aware that there are actions that are morally good and those that are morally bad. Some animals can know what human beings want and they can appear to know when they have done “wrong.” But, unlike us, they do not have ideas of moral right and wrong. They only know what the “rules” are, not about any independent ideas of right and wrong.
There are other things that make people human, but I would argue that these are the most important.