Jim Henson started making television programs starring his distinctive googly-eyed creations — part puppet, part marionette — in the 1950s. And they were hits. Early versions of Kermit the Frog, Fozzie Bear and Cookie Monster made the rounds as guest stars on variety shows. But Henson’s Muppets were typecast. Although fuzzy and feather-covered, they were, at first, considered entertainment for adults. They even appeared on “Saturday Night Live” in the show’s early days, when