Soviet cartoons.

It's overly simplistic. Even one of the most child-oriented cartoons, "Winnie the Pooh," has more hidden meaning than Tex Avery or something similar. Even "Kitten Named Gav," which is aimed at preschoolers, has hidden meaning. Take, for example, "Let's be afraid together!" Idealism is present, yes, but that's a characteristic of the time when the country was populated by builders of a bright communist future. In some ways, it was even good, at least better than it is now.