Agree with you on what we should represent as a software library. People tend to search and query for pockets of information in a library. Libraries tend to index and organise to make this easier. Libraries also tend to manage versions (aka editions) of this information. Where as individual packages manage isolated pieces of information; there can be a version set on them but they are unaware of other versions much like a book

However, in terms of calling individual bundle of information, books, might be a hard sell for everyone accustomed to what a book represents. Term which is rarely used in the context of a software system (maybe in accounting ledger-like systems). Book is a series of information bound by the context, a story, its trying to convey. Which is exactly what an individual package represents. Book is a package and that makes sense, going back in time, throwing weight on calling a package/bundle a book might have held well.

As you've mentioned, two other common terms are package and a bundle. So one way I could see myself looking at this is: a library, such as NPM/apt, contains packages, and a package is a book or a collection of associated books.