The sentence that directly answers the question asked.
The author quickens the pace of the story to build suspense in the excerpt.
No, the children were not mature about how they were supposed to survive, but adults would be. For example, at the beginning of the book, all the boys split up into groups, adults would stick together and work together. Another reason is at the end of the book when of group of boys set the island ON FIRE. Adults wouldn't cause a massive conflagration like that.
