It's a bird! It's a plane! It's the superhero genre!
Back then, I could watch Max Fleischer's Superman cartoons forever and never get bored. Today, the case is almost the same. Oh, those films have some of the finest animation I've ever seen--even by today's standards, the animation is phenomenal, right from the fluidity of the movements of the characters to the uncanny weight of the objects. The characters and objects had shadows too.
May contain spoilers