...there was Hanna-Barbara and their offerings in the mid 60s, when you could still do traditional cell animation on the cheap, but only just.
This is a brilliant TV show for kids that aired on Saturday and eventually Sunday mornings, as well as sometimes serving as the cap of late morning cartoon offerings after it's initial run in the 60s.
Huck, the inventive hay seed with his ragged pants, straw hat and vest, Tom Sawyer the more citified but still southern boy, and Becky, the caring female of the trio. They travel from one story book to the next, venturing beyond Samuel Clemens initial offerings, and shedding the shackles of literary convention to see the world. Other authors are mixed in with Mark Twain's characters, and give old settings and stories new life with the mish-mashing of characters in settings distinctly apart from their usual experience.
The three young adventurers go from the South Seas, to India, to Europe, to the Arctic and worlds beyond. Contrary to the intention of the producers, I was not induced to read those other works because of this show, but I did find the show entertaining for what it was. I can't say I initially liked it a great deal, but it was engaging. And, after a time, it just became a habit to watch. In this sense, it was a good show. It was different from all the other animated offerings at the time.
Additionally, the show was a half hour long. So it was a long "Serious" cartoon so to speak. Great adventure stories, clever, smart and adventurous characters who knew how to handle trouble and danger, as well as make new friends.
It's an oldie but a goodie. They don't make 'em like this anymore, but I'm sure someone will revisit the concept.
Regrettably there're few episodes available. It would be one of the few Hanna=Barbara cartoons I'd purchase.
If you get a chance, give it a look with your kids and enjoy. :)