The Jim Henson Co. is having a busy pandemic. Ten new episodes of the Disney+ series “Earth to Ned,” a semi-improvised talk show hosted by a big puppet alien — and one of this writer’s favorite series of 2020 — launched in January. As of last week, Disney+ also hosts Henson’s prehistoric, satiric family sitcom from the early 1990s, “Dinosaurs,” a sort of puppet Flintstones minus the humans, with — imagine that this is a rooftop and I am shouting from it — all five seasons of “The Muppet Show,” the foundation of modern Muppet mythology, following Feb. 19. (Disney has ...