Yes, the animation renders the mouse version of the American dream very interestingly. And Fiefel ends up being a self-made mouse.
But from illusive ideas shown at the beginning to the happy ending, there are a lot of twists and turns (as far as I remember, caused partly by the existence of malicious cats). How does the film deny the simplistic illusions about America but then still re-inscribe the basic message of the American dream? What does it hide or distort in trying to keep or restore the happy outlook of life?
In other words, I think you can analyze the text and subtexts in more details.