Peter Parker is written as a down to earth character so it makes it easy to relate to him. Everyone can relate to being rejected, fear of rejection, regular problems from High School. being made fun of by insecure jerks, aholes, and just about any other kind of problems that regular people encounter which Peter Parker deals with.
Just about anyone has had a baneful problem of some person doing something bad to them. Spider Man's girlfriend Gwen Stacy was killed by Green Goblin. We can all relate to rage of wanting to take revenge like Spidey after a deplorable incident. We can also relate to the struggle to let go, and move on.
It's easy to be crude, and negative but to be a positive kind and optimistic is hard. Both Ronnie Raymond, and Peter Parker are those kind of people which people can relate to.