Spider-Man is arguably THE definitive down to earth, every-man superhero, especially before things got dark and gritty back in the mid-80's. Loads of his story arcs were about things like personal relationships, financial troubles, the health of his family members, etc.

Even in his 21st century movies, we see this. In the early 00's, when other superhero movies had Wolverine being an amnesiac while preventing genocide and Bruce Banner the genetic researcher fighting mutant doggos, Sam Raimi's Spider-Man used relatively common and relatable concepts like "being scared of bullies at school," "living up to the expectations of your parent figures," and "isolating yourself from friends and loved ones through your own mistakes."

What I'm saying is that for many people, Spider-Man is the most relatable character from a list of pop culture icons. So even in a fantasy, it's easier to self-insert themselves in the role of that character.