Orthodox (and broadly, "Rabbinic") Judaism place equal weight on the "Oral Torah" – a set of evolving traditions and insights which orbit the written books in vast and intricate constellations. To deny the validity of the Oral Torah is considered heretical. If you were to just follow the 5 books, and nothing else, most modern (Orthodox) Jews would say "that's not Judaism [as we understand/perceive it]".

For a bit more info I found this Quora question, which has some good answers: https://www.quora.com/Do-people-of-the-Jewish-faith-interpre... (Only the first 3-4 answers, after which the answers divert into jokes, and a very odd fire 'n brimstone answer.)