Biggest Impact Humans Have Had on the Planet

After watching Earth After People, I think that without humans, the earth would go back to the way it was before when there was no buildings or signs of civilizations. Animals would run free and live by the idea of survival of the fittest. The world would be darker because there would be no electricity or light. I think the biggest impact that humans have on the planet is our ability to control areas and build things on top of it. We don't let things such as plants or trees take over the planet but instead we make things organized. We also have negative impacts on the planet such as pollution and overusing the earth's resources.