What makes us human is our ability to LOVE.
Animals mate for the sake of the survival of their species. They don't go in partners of opposite genders because they love each other but it is a natural instinct that they do it to multiply.
Another thing is what we call MORALS. That is, we know what is right and wrong. Like for example, killing other people or hurting them is wrong. In animals, when one animals get killed, the suspect doesn't get punished nor does the victim mourned.