Kid's Networks basically will not look at your show pitch if the main characters aren't children unless you're trying to sell them on recycling an established superhero franchise. https://twitter.com/thecartooncrave/status/1383088877880107011

It sucks, man, there are so many cool ideas that are dead in the water because the main characters aren't 12 year olds. Like, If they were trying to pitch Spongebob, Regular Show, GI Joe, Looney Tunes, etc for the first time today they wouldn't get greenlit.

I'm really frustrated that the 9-14 market that produced all the fun kinda "edgy" cartoons of our childhoods has basically dried up as Networks demand things either be 6-11 or Adult, but there aren't shorts programs that take chances on "adult" shows like there are for 6-11 stuff

Angry Beavers, Rocko's Modern Life, CatDog, Ren & Stimpy, Garfield & Friends all lack a "child entry point", Rugrats is another one that would get passed over today because they also ask for characters not to be younger than the intended demographic

Invader Zim, Pinky & the Brain, and League of Super Evil also probably wouldn't get greenlit in a modern landscape, because "bad guys" as the protagonists are balked at for encouraging negative imitatable behaviour.