Hmm.
While Blade no doubt has its importance and X-Men was the one to help jumpstart stuff in the 2000s with the team aspect...I think as far as films go, one thing to give Spider-Man credit for no doubt is proving that bright and colorful costumes can work on-screen. That's easy to say now when on TV and film they're a dime a dozen, but in 2002, that didn't happen often.
While the first X-Men is still a fine film- albeit setup for some greater in X-2- Spider-Man showed that you can do a serious superhero film, but also be light and entertaining without leaning into camp territory like Batman and Robin did. You can treat these comic properties with a level of respect and reverence for the source material without forgetting the balance of lighter elements, which is something I think Raimi managed to do in all three films- even Spider-Man 3 with its studio interference.
It opened the door, I feel, to studios trying their hands at something like a Hulk, a Daredevil, Fantastic Four, Green Lantern, and so on. The way I'm saying this makes it seem like Spider-Man was a pioneer in comic book films, and to an extent I believe it is in the same way that Batman Begins showed you can make a comic book film that's accessible as a film first, comic book film second, but also a new way to tell the superhero origin story.
It also put you in the footsteps of Peter and made you feel like you were him at times with the spectacle. We've seen this down the line with getting right into Tony Stark's suits in the Iron Man film, but those first person shots of Peter swinging when he gets his proper costume, that final swing atop the flag pole at the end, that sense of spectacle can't be done with any film or comic property, which is why I feel the Raimi films, particularly the first two, are held in such regard even today.
The sequels of course built on this with the duality of the superhero versus the everyday individual and how difficult that balance is. Sure, not the first comic film to do so- that happened as far back as Superman II, but while there Clark learned he can't give up his happiness because he has a duty to fulfill as Superman, Peter in Spider-Man 2 learns that giving up his powers does indeed have its consequences- the person trapped in the apartment fire that never made it out- and that those given great abilities or the capacity have an obligation to live up to that role.
While most heroes probably would love a normal life, Spider-Man 2 showed that when you give up that responsibility and it comes back to bite you, the hero realizes that there are things in this world much bigger than their happiness.
Another thing- now X-Men I believe handled this better with Magneto at times, but while most comic villains are fairly stereotypical and generic in their plots, Norman and Doc Ock, while the antagonists, are made sympathetic. A villain with a simple revenge plot is boring, but one with motivations adds layers and dimensions.
Sheesh, that was longer than expected. I'm sure I can come up with more, but that's where I am right now.