The "problem" is that these heroes aren't being developed to be apart of the Avengers or Justice League teams, they mainly exist in their own little bubble, and it's why stuff like Avengers: Endgame is referred to as a Crossover. The Avengers itself is a crossoever team, same logic applies to the Justice League and the Teen Titans. The Fantastic Four and X-Men are some of the only teams that have members created specifically to be in that team as it's own little bubble.
Spider-Man is a stand-alone hero, just as Flash or Batman or Iron Man are. This means that he has his own "universe" within the larger 616 crossover universe. Because he's his own standalone hero in his own bubble, he's pretty much the central protagonist, the Main Character, the big Hero, and thus he has characters that fulfill the "just like the hero but not" tropes. Sidekicks, love interests and rivals that are all twists on the protagonist's own concept rather than random other people with no direct ties to the idea of a spider man. That is the kind of thing that always happens.
>>108850296The Flash's origin has mostly been changed in perspective to now being focused around the lightning strike rather than the chemical reaction.
