These editors often worked in different locales and in different time periods and were usually unaware of each other. No original manuscripts exist. There is probably not one book which survives in anything like its original form. There are hundreds of differences between the oldest manuscripts of any one book. These differences indicate that numerous additions and alterations were made to the originals by various copyists and editors.
Many biblical authors are unknown.
Where an author has been named, that name has sometimes been selected by pious believers rather than given by the author himself. The four Gospels, Matthew, Mark, Luke, and John, are examples of books which did not carry the names of their actual authors. The present names were assigned long after these four books were written. In spite of what the Gospel authors say, biblical scholars are now almost unanimously agreed that none of the Gospel authors was either a disciple of Jesus or an eyewitness to his ministry. Although some books of the Bible are traditionally attributed to a single author, many are actually the work of multiple authors.