How does Harper Lee show that Scout has an immature, superficial view on life

This is really only an issue at the beginning of the novel. Her ghost stories about Boo Radley and the games she, and the others, play on him show a lack of maturity. Scout also resorts to violence when frustrated by a classmate. I would be careful about calling this "superficial". Scout is still a child and the reason she develops into the character we love so much is partly because of her earlier traits. People don't grow up in a vacuum. Maturity is a result of being a child as well.