Answer:
Idioms
Explanation:
Metaphor- Is used to describe an object or action that is literally true.
EX- Its raining cats and dogs
Similes- A comparison of one thing to another
EX- You were as brave as a lion
Idioms- A common phrase which means something different from its literal meaning.
Ex- Stabbed in the heart
Ex- Kill two birds with 1 stone
Clichés are used in older books like Shakespeare and the Odyssey
This tells me that Ralph has a lot of weight on his back. Everyone depends on him which makes him stressed and not want to deal with anything. He doesn't want to be the leader. This moment foreshadow's that something is going to come up and Ralph needs to take the leader position.
Best of luck,

The theme is the central message in a literary work!
Hope that helped, even though it was slightly late :D