Why only eight people in this later version we might ask?
Speaking metaphorically: the ark could then represent Earth and the seven people represent the seven other planets. (Pluto is no longer considered a planet by Nasa.)
Continuing with the metaphor…
The animals, both clean and unclean, were brought aboard. William Stirling, in the late 1800’s, noted that the animals were the Zodiac. Cancer – the crab, Scorpio, Taurus – the bull etc. would be the clean animals and the remaining animals of the constellations of the night heavens would be the unclean animals.
And why are there only seven days in a week?