> If you had an oracle that could tell you how to get to the book you need, the navigation instructions to get to the book will be at least as long as the book, on average.

This isn't quite true. Natural language text compresses extremely well and you would only need length equivalent to the compressed form, not the original form. And if you wanted to go further, you could use a mapping where extremely short strings map to known popular books and only unknown works have longer encodings.

I suppose this would work if the library was arranged such that comprehensible books were closer to the "origin". The workings of the "real" library of babel are supposed to be more inscrutable though.

But if I built one, it would totally work that way.

Kolmogorov’s library