I’m a fan of Steven Universe and Justice League Action. Each episode of both is about 11 minutes long, though.
I always try to get people hooked on the Chopra Mahabharat serial. (The whole thing is on YouTube with English subtitles. 94 episodes of about 40 minutes each.) Do you think they would appreciate a 2000-year-old epic tale of moustachio’d Indians hitting each other with maces, while pausing every so often to monologue about the meaning of it all? The Little Krishna cartoons are also good, and younger kids might like that better.