“For example, a pregnant woman says, "my water broke" to signify the coming of life?”

Can’t say I see anything allegoric in this example, “my water broke” is about as literal as woman can get to indicate that she may be about to give birth.
But, let us consider whether the Biblical or any other global flood stories are allegorical; an ancient Egyptian proverb says: “Each man thinks his own horizon is the limit of the world.” So if the limit of my horizon was Krakatoa a century ago, the resultant Tsunami would have produced worldwide flooding. We now know that the effects of Krakatoa’s collapse were felt well beyond its horizon.
It is the contention of the evolutionist that allegories represent the highest form of human thought; and thoughts evolve out of our own human experience and observation; therefore all allegory has a natural genesis whether it’s terrestrial or celestial, human or divine.
Another ancient Egyptian proverb states: “Popular beliefs on essential matters must be examined in order to discover the original thought.”