If you mean the flood…
The original myth, which was evident in numerous ancient cultures, probably grew out of the experience of a real flood which devasted much of the local area. As it was told and retold around the campfire, some (maybe children) asked how people and animals survived such a thing. Well, someone must have built a boat and saved some of everything. The author then uses the interaction of God to teach the truths about God getting pretty angry about sinners and also having mercy to save and protect the just. It doesn’t matter whether the event occured or not - the intent of the author is to teach this truth.
The worldwide aspect may have come from questions such as “Why are seashells (fossils) found high up in the mountains?”. Since there was no understanding of the geologic sciences, the only logical answer at the time was that the sea must have been higher than the mountains at some point, so obviously there must have been a massive flood. God must have caused the flood because to the people of the time, God directly caused everything. We know that storms are caused by temperature and pressure variations, disease is caused by germs and the stars and planets follow the laws of celestial mechanics BUT the ancients knew nothing of this and attributed all such things to God’s pleasure or displeasure with their actions.
The church’s document on scripture interpretation, Dei Verbum, requires that we consider the non-literal interpretation:
“The interpreter must investigate what meaning the sacred writer intended to express and actually expressed in particular circumstances by using contemporary literary forms in accordance with the situation of his own time and culture. (7) For the correct understanding of what the sacred author wanted to assert, due attention must be paid to the customary and characteristic styles of feeling, speaking and narrating which prevailed at the time of the sacred writer, and to the patterns men normally employed at that period in their everyday dealings with one another.”
If you mean treating the bible as literal history, let me again quote from Dei Verbum:
"To search out the intention of the sacred writers, attention should be given, among other things, to “literary forms.” For truth is set forth and expressed differently in texts which are variously historical, prophetic, poetic, or of other forms of discourse."
Will people reading our history thousands of years from now assume that New Orleans was experienced a great flood because God was angry with the city or will they understand the formation and movement of hurricanes well enough to view it as a natural and fairly likely disaster?
It doesn’t matter to me if people want to view it literally as long as they don’t miss the intent of the author. It does matter to me when people try to promote the literal view of everything as the official position of church (believe it or be tortured forever…)