Dr. David Bowman is the central protagonist in 2001: A Space Odyssey. He serves alongside Dr. Frank Poole as one of the chief astronauts aboard Discovery One during its long mission to Saturn (or Jupiter, in the film version). He is a capable astronaut, and the story mostly centers around him and his journey and experiences. After the ship's sentient computer Hal 9000 kills everyone else aboard the spacecraft, Bowman disables the computer. He then must continue the journey by himself and uncover the true purpose of the mission, all the while dealing with the extreme isolation of solo space travel.
After encountering the monolith and passing through the Star Gate, Bowman is transported across the galaxy. At the end of the story, Bowman is transformed by the alien civilization into an incorporeal star child. In this new powerful form, Bowman can travel across space instantaneously and reaches an intellect unmatched by his previous corporeal form. In the subsequent books in this series, Bowman continues to play a key part in protecting the people of Earth from their own self-destructive tendencies.
Bowman's importance lies not so much in his development as a character. Instead, he allows the book's readers to experience the events of the story.