Book with Animal on Earth being invaded by humans (Humans Are The Monsters Trope)

The book is set up like your average "invasion" trope, where the pov is watching its home getting invaded, we’re lead to believe that we’re reading from a human POV (Or, it’s not suggested otherwise)

The twist at the end, is however, that humans are actually the enemy! They’re the invading species, and the POV we’re been reading from is actually a Sloth.

It was probably a really obscure book, published around the 60’s/70’s.