Why are the necessary to have a healthy ecosystem?

It is necessary to have a healthy ecosystem because all our food and nutrients come from plant and animals. If we don't have that than we can't get our energy. There are also pollinators like bees or humming birds that provide plant life. Pollen is moved by these pollinator and make "seeds". A lot of our food is dependent on this co-evolution. When plants are unhealthy animals would sooner or later get the same treatment. Herbivores start to die. Then, there is no food to provide for the carnivores. The food pyramid or cycle breaks. Humanity starts to fade away. Society crumbles...
'Inhales' wow