I just turned 18 and have loved american cartoons all my childhood.
I grew up watching them from when I could speak, the era was like 2011-2017.
I watched Ben 10 (the continuity that began 2006, not the childish reboot), young justice, danny phantom, justice league, justice league unlimited, teen titans and a lot of other DC and marvel animation.
They were all fine with showing snd talking about death/murder or similar dark themes and had artsyle that looked like it was a proper show.
Nowadays all cartoons have a childlike feel to them. From the art style, to the characters, it feels like all cartoons have just become different versions of cocomelon videos.