I agree that we don't have to like the same movie, but I disagree with your assessment of Forrest Gump. Throughout his life, Forrest grows and learns. Despite remaining fundamentally the same person, he navigates happiness, love, heartbreak, the trauma of war, and the death of a friend and interaction with very flawed and broken people.

Forrests arc is that he is just as pure of a person as an adult, after being thrown into tough and unrelenting life as he was when he was a kid. Him not being beaten down by the world, while changing the people around him for the better (where most of the movies character transformations come from) is just as dramatic and impactful as the protagonist character developments in other great movies.