Let me answer some of these questions:
Who wrote/created the bible? Priests, rulers, philosophers with the OT being written in the 3rd and 2nd centuries BCE and the NT mostly in the second century CE
What is the bible? A vast collection of literature. whose canon is still undecided.
Why are there only 66 books in the bible (why not more or less)? The Catholics have more the Ethiopian Orthodox have alot more. The Jewish bibles have alot less.,
How were the scriptures used in Christ Jesus's time? I doubt he existed. However in the 30s most of the OT was written (I doubt Esther was until the 50s,60s) and according to Josephus there were four different Jewish religions ranging from the Pharisees who were Zoroastrian Jews, The Sadducees who were Hellenistic Jews and the Essenes who were Gnostic Jews. The fourth group was simply Jewish Terrorists attacking Romans on the streets (Zealots)