How is mankind important to nature?
The classical division of humans and animals has always been self-centered and artificial. Humans are animals, competing with other organisms under exactly the same rules. Evolution involves trade-offs, strategies, and adaptation. Humans have been set on a path to use their brains to compete, rather than claws. But the concepts are the same. It happens that this is a very effective strategy, such that humans now dominate virtually every ecosystem on Earth, to the point that some are now calling the age we live in as the "Anthropocene". Humans are the apex predator. We now have no natural enemies, however as vectors of disease, mosquitos control our populations more than any other animal.