What are the main motifs or themes in Coming Through Slaughter by Ondaatje? What was Ondaatje's purpose in writing from such confusing viewpoints?

The novel tells the story of a renowned but neglected jazz musician in New Orleans, Buddy Bolden. Themes include the harsh demands of the creative life, and the hazy, sometimes vanishing line between creativity and sanity. The motif of jazz helps hold the story together.
A cornet player who contributed heavily to the innovative Dixieland style, Bolden nonetheless did not enjoy the fruits of fame during his lifetime. In fact, he abruptly disappeared from his normal life for a period of time, and the search for him provides much of the novel’s suspense. Furthermore, after he was located, he suffered from numerous problems, including alcoholism. Although he felt satisfied, even elated at some of the music he produced in that time, he later suffered a complete mental collapse. Bolden was committed and remained in the institution for more than twenty years, until his death.
While using numerous viewpoints may confuse the reader, this approach is consistent with the multiple characters who were involved in Bolden‘s life and times, including a detective and a photographer. Also, because he was a jazz musician, Ondaatje likely intended the pattern of the book to approximate the sometimes discordant, sometimes harmonious rhythms, or syncopation, of jazz.

Motifs and Themes
The main motifs and themes in Coming Through Slaughter by author Michael Ondaatje include the senses, creativity, sanity, and self-destruction. As an artist, Bolden sees the world in shades of color, in sounds and smells. The story's early setting is a pleasant sensory contrast to the horrors Bolden experiences in the underbelly of the New Orleans Red-Light District. Creativity is a theme that runs throughout Bolden's story as a musician and an artist, and it is creativity that leads him into madness.
When Bolden finally returns and joins a jazz band for one last performance, he reaches the peak of his musical career. In his mind, that performance is the culmination of all he has worked for and he will never get better than he is in that moment. He sees a strange girl who somehow anticipates his improvisations through her dance and Ondaatje suggests that this experience is what pushed him beyond the limits of his sanity. In this sense, creativity is both Bolden's reason for existing and the vehicle of his self-destruction.
Structure and Points of View
While confusing at times, the shifting points of view used throughout Coming Through Slaughter serve the purpose of introducing elements of the story through different perspectives. There are many events in the story after Bolden's disappearance that must be told through Webb's perspective. This enhances the suspense in the story, which is, at its core, a mystery. The early part of the story is told through Bolden's point of view in order to set up his character and introduce ideas and facts the reader can use to explain his disappearance through the detective's eyes. When Bolden finally returns, the reader is left to wonder what happened to him to cause such a significant behavioral change. Without the shifting perspectives, Bolden's story would lack such suspense and mystery.
The shifting viewpoints also mirror Bolden's descent into insanity. As the story progresses, his thoughts become more disorganized. Fragmented sentences such as "swimming toward the sound of madness" echo this theme on a smaller scale.