"Universality" as a literature term means some factor in the book that is not particular to a specific place, people, or time period. It could be happening to anyone, anywhere since it is "universal". For instance, all humans love, hate, seek revenge, nurture, envy. These are universal traits.
In this book, one universal trait is that Raju is a scamp who becomes well-respected and saintly. This is the typical rags to riches story that you will find in almost every culture in the world.
Another universal trait is that Raju dies so that others may live. This is considered the ultimate sacrifice, and martyrs are found in literature all over the world as well.
Go back and look...what else happens in the book that is not specific to the continent, culture, or town where Raju lives? If it could happen anywhere else in the world, it is a universal trait.