The book starts out with Wade (protagonist) being poor but by the end he turns out very rich because he found the Easter egg in Oasis
It helps us understand character development.
In the book Wade starts out poor so the reader might think he is going to stay poor. Later we find out that Wade becomes rich by winning a competition where the winner becomes very wealthy.
Wade is timid in the beginning of the story but he becomes more confident as the competition goes on which leads to him win.
We can predict the plot because often in stories the shy kid overcomes his shyness and comes out ahead by the end.
In Ready Player One Wade has to find keys to open gates that lead to the end prize. He has to find three keys so this pattern repeats.
The literary elements the keys helps us understand are plot and symbolism.
The author brought this up a lot because it is necessary to the story line. The keys represent the players being able to move to the next level and without them the story would stop.