The protagonist in daniel defoe's the life and adventures of robinson crusoe belonged to the middle class. what was the effect of portraying him as a youth belonging to a middle-class family (rather than an upper-class family)?

The author wanted to get more audience by doing this. Additionally, Defoe always depicted the struggles and conditions of the middle class. Indeed, the writer himself was also from middle class family. There is a book titled "Daniel Defoe and Middle-Class Gentility" which discusses it deeply.