Galapagos by Kurt Vonnegut. What caught my attention most in this book was the narrative structure. The narrator has witnessed an entire timeline of events, but describes them in a patchwork, here and there, before things begin to fit together, hinting at this or that and providing clarity later. Along the way, there are thoughtful and humorous reflections on humanity.
I can see why reviewers liken Vonnegut to Mark Twain. They’re both humorous authors, although this novel is the only Vonnegut I’ve read, so I don’t know that he’s always like this. But it reminded me of this from Twain’s How to Tell a Story:
The humorous story may be spun out to great length, and may wander around as much as it pleases, and arrive nowhere in particular.