The Question and Answer section for Lord of the Flies is a great resource to ask questions, find answers, and discuss the novel.
I think the surroundings are merely a setting that illicit what is already within the boys. The point of Golding's social experiment was to show the true nature of humanity within the boys. Most of the boys gravitate to the darker side of human...
Ralph appeases Jack by giving him control over the choir.
They knock down their sandcastles.