Piggy tries to do what’s best for the boys, but he has no authority because the other boys don’t respect him.
A thesis statement is a clear, concise statement in which you state your position. Since you are writing specifically about Piggy, you will want to address the lack of respect the other boys have for him, despite his importance and ideas.
In Piggy's case, a thesis statement could focus on Piggy's duty as a desire to help, and impotence in not being able to.
Piggy feels a duty to guide the boys, but he has no authority and therefore cannot accomplish his duty.
Piggy makes a valuable contribution in several ways. First of all, he is organized and intelligent. He has ideas, and tries to share them. Despite the fact that they almost never listen to him, he still tries.
When the boys choose Ralph as their chief, they are not entirely sure why.
None of the boys could have found good reason for this; what intelligence had been shown was traceable to Piggy while the most obvious leader was Jack. (ch 1)
Ralph’s leadership can be traced directly to Piggy. He advised Ralph to blow on the conch, first of all. Also, Piggy does serve as advisor to Ralph. The two boys are the first to find each other, and have a bond of sorts. Ralph does make fun of Piggy, and in fact ensures that he keeps that horrible nickname. However he also listens to Piggy from time to time.
Piggy is also valuable because the boys use his specs to make the fire. However, when Piggy's specs are valuable, he is not. He can barely see without them.