This is a rather general question, but I think that you could approach this novel in a number of different ways. Perhaps the most fascinating is the story of the book (the Haggadah) itself. The little-known stories of the Sephardic Jews in medieval times, and their connections with the Arab and African Jewish worlds of that time, are very interesting. Since the book's origins are not fully revealed until nearly the end of the book, this story forms the central thread. It shows how many people contribute to its formation and transmission through the ages, and how both great (wars, political upheavals, and genocides) events, and tiny ones (the obtaining of the clips by the Viennese doctor from the syphilitic bookbinder, and their conversion into earrings for the doctor's mistress) have effects on the form and fate of the object.
The "People" of the title, however, seem to be the author's main focus. You could choose a character (the artist Isabella, perhaps, or Lola) who particularly interests you, and discuss how that person is important to the story.
The "frame" story, the modern tale of Hanna the book restorer and her family problems, might interest you the most. How does the story of Hanna's life contribute to the unfolding mystery of the Haggadah? How does her particular predicament affect how she acts in this story, and how might things have been different if she had had a different background?
Or, you could choose a time period in the history of the book (Sarajevo in WWII, Seville in the 15th century, modern Australia, or 19th-century Vienna) which you find interesting. Analyzing a particular time period would shed light on what the people of each time and place thought about the book, and might show more about the plot and meaning of the story.