i liked it ,it was dumb fun but...

the ending butchered the fourth wall really bad,it's usually cool when it's subtle ("your advantage is popularity") but it was just too much on thiat part

i also think they could've stretched it a bit,he deals with the marvel universe so quickly it almost makes you wonder how noone else had did it before him

the whole thing seemed like an inside joke when it felt like it could be much more,the part above for example as simply amazing

Your second point was my entire problem with the entire series. He killed everyone so easily that it didn't really make sense. Prime example, Spider-Man's spider sense should've kicked long before Deadpool could shoot him.

take it as a lucky shot,there are an infinite number of marvel universes which means there is an infinite number of universes where he went mad,which means there is at least 1 universe where he had a series of flukes one after the other sucessfully killing every hero/villain in succession

it might sound dumb but my brain has this obssesion with trying to fill plot holes

The explanation makes sense, in a cosmic sort of way, it's just unnecessary. I get that they weren't trying to write the best comic series known to man or anything, but that was really lazy writing. The only thing I really liked about the series was the Taskmaster stepping in.

i'm just getting into him,but i really liked seeing his more "depressing" repressed side on this series,for me that was the highlight (i dont know if it was shown in other comics of his cause i'm REALLY very early on his comics) and it makes me sad it wasnt expanded further,it really made him into an even more likeable and relatable character for me

I haven't read it yet, but Deadpool Dead may have what you're looking for. It's basically him trying to kill himself.