"nouveau, nouvelle, nouveaux, nouvelles" has a subjective meaning, since it means "new to me". So, it is placed in front of the verb.
When the thing is "brand new", there is another adjective: "neuf, neuve, neufs, neuves". This is an objective (factual) qualifier, and therefore it is placed after the noun.
- ma nouvelle voiture = I bought it recently, and it was second-hand or brand new when I did.
- ma voiture neuve = I just bought it and it was never used before.
"Un nouveau livre", for the same reason. The making of the book is not so much in printing it but rather in writing it.
So, yes, "un livre neuf" (never used/read) will be just out of the printing plant, even if it is the 12th edition and/or the writer died 2 centuries ago.