Today’s software tools have weird names. We call a “library” some collection of functions that you can use in your program.
I think that software repositories (where apt downloads your programs from) should be the actual libraries, since that’s where you go to get your information; Meanwhile individual packages of information should be called books because they are one solid object containing a bundle of information.
I think repository makes more sense than library. A ‘repo’ is also a large storage of something that is very often indexed and catalogued for easy retrieval as well. It also at least ‘feels’ more appropriate for something usually remotely accessed, like package manager repos.
Of course, my well has been thoroughly poisoned on this topic, but I generally agree with others that an analogy doesn’t and shouldn’t have to carry through all the way.