So let’s say some intergalactic alien race, let’s call them Kanamits, came up with a special use for humans and took us all with them to their planet. What would happen to this third rock from the sun?
Well that’s depressing. If humans disappeared, the world would be a better place from nature’s perspective. It wouldn’t take that long: 500 years or so. And 500 years is nothing in the life of a 4.5 billion year old Earth. Hell, 500 years is nothing even if you’re deluded into believing the Earth is only 6,000 years old.