It seems that in nearly every superhero book, it is always humans that get to be the heroes. There are a few exceptions of course, but on the whole, humans all the way.
Now that is down to people being able to relate to the characters. But what about Squirrels? Who do they have to relate to? There is Squirrel Girl but that is about it. Why not have actual squirrels as heroes? It can be done, just see below.