Simplify the following text for a Grade 8 native English-speaking person.
Original: As Gregor , Enola , Helen and the others land on the island and find past traces of civilization , including the skeletons of Enola 's parents , they begin to start civilization anew on the island , but the Mariner decides to leave .
Simplified: Gregor , Enola , Helen and the others start to rebuild civilization on the island .