You could essentially call him the cofounder of marvel comics since marvel comics is only famous for his storytelling and character creations that he and jack kirby created. Though he did not start marvel comics he created the characters and comics that made marvel comics popular. He was the brains behind marvel. His comic book stories are one of a kind and legends in the comic book and novel universe.
Sure anyone can create a man in a spider suite or a green hulk giant but its not for his characters appearance that he will be remembered for but his story telling.
Stan lee may have died but his famous original story lines will always be remember.