Man is a consumer in an ecosystem.
Consumer: The organism that do not produce anything on its own then consumer what they get form there surrounding (ecosystem).
Producer: The one the best example of producer in ecosystem is "Plants". They prepare there food by themselves, they are not dependent on any other organisms.
This is also known as autotrophic nutrition.
Decomposers: These are the organism that decompose the waste organic things in the ecosystem and use that organic waste as the food. They help us to keep surrounding clean and also help the farmers to make fertile land