The writers of the Bible were real authors

The incarnation is an incomparable mystery -- the Word made flesh in the person of Jesus of Nazareth, fully God and fully man. That mystery is reflected in how the Bible came to us, and is preserved in the doctrine of organic (as opposed to mechanical) verbal inspiration of Scripture. Here's Louis Berkhof:

We cannot explain the interpenetration of the divine and the human factors in Scripture, any more than we can explain that of the two natures in Christ. Scripture presents itself to us as an organic whole, consisting of several parts, that are interrelated in various ways, and that find their unity in the central, all-controlling, and progressively unfolding, thought of God reaching out to man, in order to redeem him from sin and to bestow upon him the blessings of eternal salvation. And therefore we should not ask where the divine ends and the human begins, nor where the human ends and the divine begins. We might just as well ask where in man the soul ends and the body begins. No such line of demarcation can be pointed out. Scripture is in its entirety both the Word of God and the word of man. (Introductory Volume to Systematic Theology, pp. 154-155)