The most important capacity that we as human beings have is our capacity to feel compassion for others and to care about them.
To be sure, our ability to reason and think is extremely important. However, this on its own would not make for a very good world. Instead, we need to have our compassion and caring so that we do not simply treat others horribly and make our world a sort of living hell. If we did not feel compassion for other people, we would do things like killing them whenever we wanted to take something from them. This would be a truly horrible thing.