Thank you for the question on the authorship of the Bible, “Who wrote the original Bible?”
For one’s consideration, the author of the Bible is the Holy Spirit who guided men to record the Words from God.
II Timothy 3 says this, 16 All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, 17 so that the servant of God[a] may be thoroughly equipped for every good work” (NIV).
I Peter 1 says this, “20 Above all, you must understand that no prophecy of Scripture came about by the prophet’s own interpretation of things. 21 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” (NIV).
The Scriptures declares that God himself worked in a supernatural way that the prophets and apostles were carried along by the Holy Spirit in writing their scrolls or letters.
Since the Bible is a collection of writings of what we now called the 66 books of the Bible, they were later compiled into one book, known as the Scriptures or the Bible. One of the earliest compilations of the “Bible” happened sometime during the 4th CE with the Codex Sinaiticus.
Summary: God is the author the Bible and its compilation was formally recognized during the 4th CE by the early Church Fathers.
-Kingston