Ironically, the people snubbing their noses at the ludicrosity of "rock monsters" in their Noah story don't acknowledge the same scale of absurdities that come with believing in this story as literal history. "Noah" stays creatively and intelligently within bounds of its source - the rock guardians don't alter the vague story as it is written. They aren't ever mentioned in the text, no, but then neither are the dinosaurs. The story is even more outlandish, not less, without them or some other kind of unwritten supernatural assistance in building the ark and protecting both it and Noah's family against all the lives surely trying to violently escape their doom. In truth, the written version is useful to us mostly as a parable exploring our ancestors' perceptions of their humanity and worldly place, and the movie successfully nudges the arguments into relevancy for our own current debates, fears and hopes for mankind's future.
Rather than just an excuse for another apocalypse movie, this is a study of the Bible's depiction of human nature, and a character study of its god and of Noah. This is the one time in the Semitic religious texts where man teaches its god something about the preciousness of life here on earth, and its god listens and agrees ...for a little while. But it's easy to see that the Bible's man is just as dark as its god, since just after having witnessed all of human and animal life destroyed, save for the few on the ark, Noah, supposedly the best of humanity, has such a poor perspective that he curses his own son's lineage into being "the lowest of slaves." That part was politely altered in the movie since it's a bit of a buzz-kill for mankind 2.0, but it doesn't make it into the Sunday school teachings either.
Of course, the world's pre-flood history as written in Genesis would have to have come through Noah and his family of survivors. Aronofsky includes the tradition of verbally passing down these chapters, but he ingeniously deconstructs the narrative we see in Genesis today into two perspectives, starting from the beginning when there was nothing. First we hear Noah's version, centered around the creation of a harmonious world, pure and holy, except for man; then we hear Tubal-Cain's version, centered on man as the only creature created in god's image and master of the world's creatures to do as we see fit. By splitting the first chapters of Genesis into two different perspectives, Aronofsky breathes life into the text as a cultural collaboration of early mankind battling then as we do now over the always clashing values of living conservatively and harmoniously or pursuing power and self-fulfillment.