Without any oxygen we would all die and that's why we have to have a lot of plants around. We are also destroying our Ozone layer which protects us from ultra violet rays that would kill us. The presence of free oxygen is quite remarkable from a chemical point of view. The oxygen in the Earth's atmosphere is produced and maintained by biological process. Without life there would be no free oxygen.
Earth is the only planet known to have living things on it.
We have been trying to look for other traces of life out there but still comes out empty handed. Earth is so unique, as is all the rest of the planets, but to have this many people living on it is unreal.