I wonder if it would be possible to put in some sort of rope/pulley/basket system so a person on the higher floors could lower books to a waiting person on the bottom and vice versa.

I would imagine that would be at least a little easier, and probably faster and safer, than carrying loads of books by walking down/up the stairs.

You'd have to get permission and find someone who could do a professional/safe job, but in the long run I think it would be worthwhile.