You may be interested in a detailed breakdown of authorship of various parts of the Bible [0]. In summary, to a first approximation, only the books written during the Babylonian Exile and during the preaching of Peter and Paul were written during the events that they describe, and most other books were written much later. The Gospels are decades after Jesus' life and death, and all of the Bronze Age stories are set centuries before they were recorded.

[0] https://en.wikipedia.org/wiki/Authorship_of_the_Bible