Here are some reasons why:
* Target Audience: The first book was written for a younger audience, and the tone reflects that. There are a lot of comedic moments, lighthearted adventures, and a sense of wonder that appeals to younger readers.
* Introduction to the World: The book introduces us to the magical world, and Rowling sets a whimsical tone to make it inviting and exciting. The book feels like a fairy tale, with elements of humor and adventure.
* Harry's Character: Harry is a child who is discovering magic for the first time. He has a mischievous streak and a sense of wonder that creates a playful atmosphere.
* The "Good Versus Evil" Struggle: While there is a clear evil force at play, the overall tone remains light. The evil Lord Voldemort is presented in a less menacing way in this first book, contributing to the playful atmosphere.
* The Importance of Friendship: The book focuses on the importance of friendship, loyalty, and courage. These themes are presented in a lighthearted and relatable way, making the story enjoyable for readers of all ages.
As the series progresses, the tone does become more serious and darker, reflecting the growing maturity of Harry and his friends, and the escalating threat posed by Voldemort. However, the first book maintains a sense of lightness and playfulness that makes it a classic for children and adults alike.