The primary theme in Roald Dahl's classic novel "James and the Giant Peach" is the importance of overcoming one's fears. From the beginning of the book, James has one set of hurdles to overcome after another, beginning with the loss of his parents but also including the decision to run away from his cruel aunts and make new, magical friends.
From its beginning, James' life is one of fear and deprivation. His parents die in a horrible accident, and his aunts keep him locked in the basement except when it is time to clean the house or chop wood.
A strange, wizened man gives James a bag of magic crystals, but James trips and drops them on the ground. They empower a tree to grow a huge peach, which his aunts treat as a tourist attraction, but it also hosts some large insects, worms and spiders who had eaten the crystals.
The peach snaps off the tree, rolls over the aunts and makes its way all the way to the Atlantic Ocean. Sharks, hailstones and weapons from the Cloud Men do not deter them, in large part due to James' clever stratagems. The crew end up deposited on top of one of New York City's skyscrapers, and they all thrive in their new home, having overcome their fears.