What we today call the Bible, is not one book, but a collection of many shorter books, written by different authors over centuries and brought together in one volume.
The Old Testament is a collection of ancient Jewish holy scripture and the New Testament is just a small part of the early Christian writings. But who chose which books would make it into the Bible and which would be cast aside?
The Prophets were a later addition to the Jewish Bible, coming after the Torah. They were accepted as canon sometime before 180 BC, but the exact date is unknown