Well, I have read SF novels which had no humans in them. Ages ago, so I cannot remember the titles. One was a fascinating story around a species that had 3 genders - which, as you can perhaps guess, really doesn't make things easier. Another one was about a heavy planet, a planet with high gravitation. All the lifeforms there were built accordingly, very compact, solid and strong. And they were always terribly afraid to fall down from somewhere, even if it was only 2 ft deep, because that would kill them instantly.
I think its a nice way to come up with something really new - but that doesn't mean its easy to do. But it leaves more room for the imagination, and has not been done so often before.