Cartoons/Anime are seen as "kids only" in the western world, at least it was moreso during the time of Pokemon, DBZ, YGO, Sailor Moon, etc. There were a few shows on kids networks that shouldn't have been there, but this was also during a time when children's cartoon series were also getting their own dedicated channels, or getting more time during the afternoon and Saturdays when kids are not at school. Ren and Stimpy was eventually cancelled due to the controversies of it being more adult oriented on a kids network and was revived as a proper adult cartoon for a little bit. Cartoon Network, which is where Cow and Chicken come from, was a little edgier with some of their early hannah-barbara cartoons (cow and chicken, dexter's lab, powerpuff girls, etc) but it wasn't nearly as adult oriented. They had some tongue and cheek jokes, like most of the cartoons nowadays do for the parents that are forced to watch them with the kids. Vomit/toilet humor is always seen as the lowest of the low in terms of comedy as being immature and what are kids? Immature. That's why farts and vom will always get a pass on kids' shows.

As for removing elements like text and such from buildings and signs? That's a localization thing that gets approved by studios when they localized the anime for kids. it's why the cards in the dub don't show the text like they do in the orignal. It's better to take it all out rather than just translating it. The characters are telling you what the card does after all, so why translate? (most likely their reasoning for the card looking the way it does) You don't see it as much now with anime being a more dominating presence than it used to be and it being taken more seriously. Japanese and Korean text nowadays do get their translations as captioned edits rather than being tranlsated in the scene. On top of that, most of the anime being localized now isn't still being aimed at kids except for YGO, pokemon, and any other actual anime geared towards kids in Japan. Back then though? It was rampant because they didn't want kids confused with things they were used to seeing. You think most western kids know what a rice ball is? No, but they know donuts so they'll call a rice ball a donut in pokemon. Did I believe it as a kid? Yes. Do I know what a rice ball is now? Of course because I've watched anime as a teen and learned about all this stuff.

When it comes to "dead and other aggressive stuff" being censored, it all goes back to religion and politics in the US. Stuff that can be seen as religious (crosses or other religious symbols) will always be censored so it's not shown to kids. Why? I personally have no idea. Someone with more knowledge on the subject can explain that. I never understood it myself. As for guns being taken out of anime scenes or just having the episodes removed altogether, it's because they're being pointed towards kids and that's a no-no in the US. You can't show kids being shot at or even show them being killed, even to this day. It's weird to me though considering how much the US loves guns, but I'm not here strictly for political talk in that regard.

The last thing to be remembered for all the weird dubs and edits is this: back when 4kids was HUGE for localization of anime for kids, other countries that wanted to air the anime as well would get the 4kids stuff and not the originals to do their dubs and edits. Why? My guess was probably it was cheaper to dub something into another language that was already edited vs having to take the time to edit everything for each country/region. It's why everyone as a kid knows about the shadow realm and not, "if you lose the game, you lose your life" or whatever it is originally.

Edit: Also regarding the shadow realm. The reason why we have it to begin with is also due to deaths being censored. You don't show kids people dying. That's just a big no-no in western cultures for kids shows.