Humans are mammals. They are also social animals. They usually live in groups. They help and protect each other. They care for their children. Humans are bipedal, which means they walk on two legs.
Humans have a very complex brain, which is much larger than that of the other living apes. They use language, make ideas, and feel emotions. This brain, and the fact that arms are not needed for walking, lets humans use tools. Humans use tools far more than any other species.