Thoughts on NW

The fragmented stories of the four main characters in NW perplexed me. The book is composed of fragmented words and scenes. And none of the characters have a happy ending, which is what we typically see in novels or movies. The book is not like a mosaic that put broken things together as a whole, but let broken things staying broken. Why does Zadie Smith set the book this way and what does she trying to say or show? Another thing I noticed is fate associated with roots. Natalie, or Keisha, tries to leave her root behind but somewhat still can't shake it off. She leads a perfect life by pretending to be someone else but . In the opposite, Felix accepts his roots and turns into a better person, but he dies. Is this because their fate will follow them no matter what they do or who they become? Is it pointless to try to get out of the poverty they were born into since their roots will follow them along the way?