May as well just say The Earth would be better off if people had never existed if you're going to go that route.
There's more people living better lives, so things are better. There are new problems caused by our previous success that we solve next.
There's more people living better lives, so things are better. There are new problems caused by our previous success that we solve next.
If you don't care about homo sapiens, then global warming isn't really "bad" - the ecosystems will adapt.
No, that most certainly doesn't follow. It's entirely usual and normal for an amount of something in a system to be fine but then an excess of the same thing to be not fine. This is a very common situation in medicine, for example.