Polite reminder: Earth is a tree planet with some bacteria. Everything else is just the extra stuff that lives here too.
@InvaderXan Can we say that humans are just parasites, who are slowly killing the host?
@SeventhMagpie Certain types of human do seem to fit that description. But I think it's more that humans are a component of the system which is out of balance.
Any little ecosystem, from a fishtank to a sourdough culture, can get out of balance sometimes. It might mess stuff up for a while and do some damage. Eventually though, the system needs to find a balance, and usually does.
Humans just need to realise that they're part of such a system and learn to balance themselves within it.