Kim is the character who changes the most throughout the story, because Kim is the story of his adventures and growth. These changes are due in part to the death of Kim's parents, including Kimball O'Hara, his father, who dies of addiction and leaves Kim orphaned; this makes Kim's father a very unlikeable character. The drummer boy whom Kim is forced to spend time with at school is also very unlikeable, as he's ignorant and abusive.
Kim has a happy ending for a young boy who grew up without parents; it shouldn't be changed. Kim's relationship with the lama is celebrated, and Kim has a better understanding of himself. The only way that this story might benefit from a different ending would be if Kim's future security was more elaborated upon. The world the characters live in is a dangerous place, and even if their spiritual clarity is assured, their physical safety is not.
The lama is one character who has many fine qualities. One of the most important is his empathy and love for Kim; like Kim, the lama also gains an understanding of himself throughout the novel.
Most people experience some kind of adventure, like Kim, in their lives, though few are as extreme as what happens to the young boy. But learning about who you are and what relation you have to the world is a universal experience.
Kim is written from the third-person perspective. If it was written from Kim's perspective, other characters, like the lama, might be less sympathetic and less understood, but Kim's inner workings and motivations might have been more clear.
Kim could have occurred in real life, to some extent, though many of the things that take place are fantastical in nature and might not line up exactly with the true historical events. Still, though, there are people who live lives that are strange, confusing, and full of wonder—so Kim and the lama's journey together is something that could have, in some capacity, happened to someone in the world. However, a lot of very coincidental meetings and events drive the plot, which makes it less likely that the events could happen in a normal life.
Themes in Kim include identity and war. Kim's adventures take place with the backdrop of war and are often driven by it. Kim and the lama—as well as other characters in the story—search for a sense of identity in a shifting and transitive world.
The depiction of India and the effects of colonialism by the British are major things that make Kim significant. Though there are several problematic things about the book in a modern context, it still shows that many of the people who supported colonialism didn't understand Indian customs or culture. It also shows the negative consequences of colonialism for many of the people in the country—including Kim.