There are definite differences in Ralph's character from the beginning to the end of the novel. At the beginning, Ralph is seen frolicking in the ocean without any major concerns. He makes fun of Piggy and gives him his unfortunate nickname that is the only name by which Piggy is known throughout the story. Even at the end of the first chapter, Ralph, Simon, and Jack are exploring the mountain and Ralph spreads him arms, exclaiming, "All ours." At the start of the second chapter, Ralph is enthusiastically leading a meeting of the boys, setting up rules, and dividing tasks. As the story goes on, Ralph becomes increasingly frustrated and increasingly less carefree. In chapter 5, he calls a meeting, which turns into a chaotic farce, and calls for a vote to determine whether or not they agree to believe in beasts and/or ghosts. He is ridiculously trying to legislate belief. By the time the story gets to the final chapter, Ralph has watched both Simon and Piggy die. He is being hunted like an animal and he realizes that to survive, he must think like an animal and be prepared to kill another person if necessary. When the British naval officer appears on the island to rescue the boys, Ralph finally realizes what the problem was on the island and in the world - that mankind is essentially evil. He has become a boy mature far beyond his years. He now weeps for the loss of his friends Simon and Piggy who Ralph now knows was as loyal and good a friend as he would ever know.
It is clear that at the beginning of the novel Jack represents the forces of civilisation, order and control. He is elected leader of the boys and is dedicated to maintaining control and being involved in meaningful action to achieve this goal. His example, in building huts for example whilst the other boys play and avoid work, means that he is respected and thought of highly by the boys. However, as the novel progresses, the forces of savagery, represented by Jack, become greater, and finally all the boys except Ralph and Piggy join Jack and his hunters.
Through the course of the novel, Ralph, like Simon, comes to understand that savagery is something that dwells within all of the boys. Although at the beginning of the novel Ralph is bewildered at Jack's bloodlust, we can see that Ralph comes to understand this personally when he hunts a boar and joins in the dancing afterwards, and even participates in the murder of Simon. Despite his best intentions, he is forced to realise that his savage instinct is part of him, as it is an essential characteristic of mankind. This epiphany or realisation plunges him into despair for a while, but it also enables him to cast down the Lord of the Flies at the end of the novel. At the end of the story, ironically, although Jack is rescued by the naval officer, his tears indicate that it is his innocence that has been lost irrevocably through the knowledge he has gained about the essential human condition.