If everything is interconnected in nature, then what role does parasites play in it?

Parasites play a very important role in nature. At first glance, it seems that they are absolutely unnecessary in the natural system and they only harm. In fact, they serve as orderlies. They balance flora and fauna. Without these creatures, the process of evolution simply did not exist. Without stimuli, no organism would need to develop, acquiring some new body parts, organs, functions, and so on. Therefore, we often underestimate parasites, although they still have the same function as millions of years ago.