Of course there are truths in the Bible -- no one doubts for example that there existed a city of Jerusalem or a country of Egypt.  That is like saying there are truths in the Iliad -- but that doesn't prove much -- few today believe in Apollo and Athena and so on.

All texts, even modern ones but even more those from ancient times, need to be read skeptically (not cynically), and texts that refer to outlandish things like talking asses and fire and brimstone from the sky and divine voices from burning bushes need a particular skepticism -- one that says the more "out" a statement is, the more evidence is needed.  Basically whenever an ancient text speaks of miraculous happenings, it should be doubted -- not just the miraculous parts but all of it -- until there is independent non-miraculous support.

This doesn't mean the ancient authors were deliberately lying, but only that they were recording stories that had come down to them in their culture -- just as the stories of Robin Hood or King Arthur came down to the Middle Ages in European cultures and later got written down as fact, when in fact they were myths.