Yes, the authors were ordinary human beings. And what they wrote reflected their own backgrounds, experiences, and particular ways of speaking. But, no, their process of writing the Bible was anything but ordinary. Here’s how Peter—the disciple-turned-apostle of Jesus—described this remarkable process in 2 Peter 1:20–21:
Above all, you must understand that no prophecy of Scripture came about by the prophet’s own interpretation of things. For prophecy never had its origin in the human will, but prophets, though human, spoke from God as they were carried along by the Holy Spirit.
What Peter describes is a divine-human partnership in which God initiates and guides the process of communicating the exact message he wants to reveal. He does this through chosen prophets and apostles who accurately record that message, but in ways that reflect their own unique personalities. Also, God superintends this process so as to prevent the introduction of errors into their writings, as these verses make clear (emphases mine):
“The grass withers and the flowers fall,
but the word of our God endures forever.”
“For truly I tell you, until heaven and earth disappear, not the smallest letter, not the least stroke of a pen, will by any means disappear from the Law until everything is accomplished” (Jesus, in Matt. 5:18).
“Heaven and earth will pass away, but my words will never pass away” (Jesus, in Luke 21:33).
“Your word is truth” (Jesus, talking to the Father, in John 17:17).
So in the end you’re reading, for example, a psalm of David, the gospel of Luke, or a letter from Paul, but each of these can also be described as Scripture and the Word of God (2 Peter 3:16). It is truth revealed by God—and confirmed through other means, such as history and archaeology, as we’ll see in other answers.
We also have the prophetic message as something completely reliable, and you will do well to pay attention to it, as to a light shining in a dark place, until the day dawns and the morning star rises in your hearts.