We are 'important' in the respect that we continuoulys disrupt and manipulate our ecosystems. For example, we directly and indirectly continuously hunt down oth

We are 'important' in the respect that we continuoulys disrupt and manipulate our ecosystems. For example, we directly and indirectly continuously hunt down other apex predators (tigers, lions, tuna, etc) - which tend to be keystone species in their environment. Removing that pressure on those species would nearly immediately modify the environment. For an example, look at the reintroduction of wolves to yellowstone. Nearly all species that we have domesticated will suffer ridiculous drops in their population. Many of them would be reduced to severely reduced niches. For example, domestic cats would have their ranges limited by winter, and have downward pressure applied from larger predators as they rebound. On the other hand, based on how well feral pigs are doing right now, pigs will probably make it huge.