This statement is not accurate. While some novels have depicted the lives of the middle and working classes, there are also many novels that depict the lives of the upper class, as well as stories that span multiple social classes. Additionally, many novels focus on characters from a variety of backgrounds and their experiences are not limited to a single class. Furthermore, there are also novels that depict the lives of people from different cultures and backgrounds, exploring themes like race, gender and sexuality. Therefore, it's not fair to say that most novels depict the lives of the middle and working classes only.