All of this diverse life is necessary to keep ecosystems going and maintaining life in general.
Genetic diversity allows species to adapt to change in the environment.
Imagine if the world had only one type of cow adapted to a climate like Virginia's. If the world-wide climate became very hot or cold, this type of cow might not survive the change. Then we would not have the milk or beef that a cow provides for us. The variety of species in the world provides many methods of nutrient and energy cycling in ecosystems. Plants use the sun's energy and provide many animals with food.