Piggy is presented as a bit of a social outcast in "Lord of the Flies." He is overweight, has asthma, and wears glasses. Because of just those three things, he is the subject of a lot of group ridicule and abuse. Add to the mix the fact that Piggy is very intelligent, and the reader can see that Goulding has created a caricature of the standard "school nerd."
Despite receiving a lot of ridicule from the group, Piggy is still willing to help out where he can. It's an amazing spirit of altruism. He doesn't owe the other boys anything, but he is very willing to share his knowledge and glasses with the group in order to make a fire.
Piggy would never be classified as an "alpha male." He relies heavily on Ralph for protection from just about everything, yet Piggy does prove valuable to Ralph. Piggy functions as an adviser to Ralph throughout the novel. Additionally Piggy is significant because he represents a civilized and well behaved society. While Jack and the other boys are devolving into murderers, Piggy never loses sight of the values and morals that adults from him pre-island life have instilled in him. Piggy continually reminds Ralph that survival is more than food and shelter. It is about rules and order just as much as nutrition. Piggy proves that right through his death.