The Bibles author is God as attested to by Christ himself
And by the way, there is such a thing as direct authorship and indirect authorship. God is the ultimate author, yes of course, but it is self-evident that He worked through human authors. These human authors were protected from error by God himself.
Now. Were these human authors granted this protection as individuals? I do not believe so—because if that protection died with them then the Church could not have assembled their writings, discerned which were authentic, and correctly interpreted them down the centuries. Rather, the evangelists were protected from error as part of the corporate protection that the whole Church enjoys—which flowed from the Apostles and still exists in the Church today.