Because there is six types in the Kingdom (of life) : animals, plants, fungus, protista, Archaea and bacteria. The humans are not plants, fungus, protista, archaea and bacteria. They are animals. The human's phylum is Chordata (vertebrate). The human's class is mammalia. It's order is primate (the same as apes). It's family is Hominidae (apes that have no tail and can gather food with their hands.) The Human's sub-family is Homininae. It's tribe is Hominini. It's genus is Homo and it's specie is scientifically named Homo Sapiens.
We have much more in common with animals than we think. Like us, some animals can make tools. The only difference is that our tools are a lot more complex. Like us, some animals have a language. The only difference is that their language contain less than ten words.