Muppets: The Next Evolutionary Step?

Just a quick thought I've been pondering, sparked by the most recent Muppets movie.

If Gary (Jason Segel) and Walter (puppet) are brothers, then that means Walter must be or have some sort of genetic mutation, right?

Don't get me wrong. I love Walter.
His mutant status in no way reduces my love for him as a Muppet.

As we all learned in junior high biology, mutations are not necessarily a bad thing. They can lead to an increased ability to survive, such as with the peppered moth evolution with the Industrial Revolution.

So my question is this: if Walter and all the other humanoid Muppets are just humans with a mutation, could Muppets then be the next step in human evolution?
Note: I recognize it's a movie, so I'm thinking of this in terms of that fictional world's reality, not our real world.

The Evolution of Man... to Muppet

It makes sense, doesn't it?

I mean, think about it. Muppets never seem to age, they can survive falls from high buildings, repeated electrocutions, they don't seem to need to eat or drink, as well as a whole host of other advantages over humans. When the zombie apocalypse occurs, you can bet rats, cockroaches, and Muppets will survive.

The only question remaining is whether humanoid Muppets have the ability to procreate and continue their species, or if they can only begin as mutations directly from humans...