This is an interesting movie but I never quite understood who Jim Henson envisioned would be lining up around the block to see this...
shareArs gratia artis.
But really, this seemed like a labor of love from all of those involved. I'm guessing Henson and co. were figuring make the film and let an audience find it.
A child of five would understand this. Send someone to fetch a child of five! - Groucho Marx
My guess (and as I say, this is just my guess), is that Henson made this film to reach adults through their children. Children would want to see it because it's puppets, etc., but the message of the film was clearly (to me) targeted at adults. The whole take care of the world, stop genocide, etc. message is not likely something that young kids would understand (though, I kind of got it but I have to wonder if that's because I was raised learning about the Holocaust, which is kind of what this movie reminded me of with the annhiliation of the Gelflings, while the average, non-Jewish kid of the time during which this movie was released would not likely have made the connection), but adults would probably get it.
As I said, though, this is merely my guess/opinion.
Fans of fantasy?
Children as well, obviously. It's still a tale of good conquering evil. It's a little dark, but that's how I personally liked my movies growing up.
Most of the best movies ever made don't have a specific audience.