Points for incliding Schnitzel and Courage but I think I'd change up some of the representation.
For example, I think Gumball is big enough to at least have Darwin or Nicole. I would inclide more Ed Edd and Eddy characters as that show was CN's Spongebob that went on for a decade. On the contrary, as much as it pains me to say it, I don't think Fosters, and (much less painful here) Cow and Chicken, and should have a 2nd character before some shows that aren't quite listed here, and I'm not too keen on Princess nor Mandark. Don't get ke wrong, those series should get more reps, but imo I would prefer Dee Dee over Mandark and... idk for Princess.
On that note, I see that modern representation kinda falls a little flat. Maybe get some Craig of the Creek there? Some Clarence? Uncle Grandpa? I do like you going way back to pull some classic CN characters, but some of them I would be fine sacrificing like Jeff the Spider and Red Guy.
My thoughts on this roster. Not bad, but I'd be a little confused on the direction.