Lord of the Flies is a novel that emphasizes the characteristics of human nature when people, in this case, young boys are left to their own devices in an uncivilzed and unfamiliar setting. As the novel progresses, the boys natural tendencies become evident - there are those who are the leaders, those who are the followers and those who are the hunters. There are the bullies and those who are bullied. The strong personalities take over, control and give orders. The weak follow the leaders because they are not physically or intellectually able to do otherwise. Boys like Simon are too sensitive to their surroundings and so are unable to survive in such a primitive and chaotic environment.
What becomes important on the island, without adult supervision, is the need for survival and so a group of the boys become the hunters. Because the hunters provide life, they are to be respected.
What also becomes evident is an overwhelming need for leadership.
Two leaders, Ralph and Jack, with two completely different souls, emerge as the protagonist and the antagonist. The boys with a higher moral character follow Ralph the others follow Jack. And so the plot and the theme for the novel is determined between the interaction of these two boys and their followers. Good and Evil become the major characters of the story.
As the boys regress to more primitive states, ritualistic chants and dancing in a circle are used to ward off the fear the boys are experiencing and the 'beast' becomes the personification of all that is dangerous and represents the horror of their situation. "Kill the beast" they chant without realizing that the beast does not exist except within themselves.
What happens on the island is the clash between good and evil in the characters of Jack and Ralph. Because there is no law and because the boys cannot agree, what was at first an adventure becomes a nightmare as fear and death and insecurity bring out
the natural instincts and personalities of the boys.