If the bible is not historical fact, how can we discern what actually happened in history as opposed to what is “mythic” religious revelation?

First of all, we know that the Bible contains enormous amounts of historical facts, many of which have been verified by historians and archaeologists. What we can say about the Bible is that it was not primarily concerned with facts. The human authors, guided by the inspiration of the Holy Spirit, set forth to relate a story of faith that took place within a historical context. This means that their focus was on the faith experience and the revealing of God’s saving grace in human history. For them, facts were secondary. As a result, there are some historical incongruities in the Bible. Despite this, Catholics confidently say that we believe in the inerrancy of the Bible. This means that, when it comes to truth about God, the Bible contains no error. It does not mean that we take every detail as historical fact. To help us better understand the nuances of historical details in Scripture, we need to rely on Scripture scholars and we are blessed to have many Catholic Scripture scholars included as some of the best in the world. Their work is made available to us in footnotes, commentaries, Bible dictionaries, and concordances. We simply cannot read the Bible without their help. To do so is folly and arrogance. Instead, as we read passages of the Bible, we can and should pause to consult such resources, to help us understand with our head, before we proceed to read again so that our heart can come to know God in his saving Word.