OK, on the question of why the Jewish sabbath is weekly, not annual – and I confess I haven’t researched in full, I went far enough to prove the point, because I think the question is inherently uninteresting.
If you read the text out of context, I can see the interpretation that “on the seventh day” means “on the seventh day of the year”, not weekly. But reading in context, that interpretation just doesn’t hold up.
First, Biblical references to the holidays (for example, the list of sacrifices in Exodus 34) mention “on every sabbath”… and “on the new moons.” The other holidays (annjual) are specified, such as “on the first day of the seventh month”. The fact that sabbath is not specified as “on the seventh day of the first month” is pretty conclusive that it is not meant as annual.
Second, the notion of the Jewish New Year signifying the date of the creation of the world is a post-Biblical interpretation. In the Bible, the holiday is a day for sounding the ram’s horn, a special holiday on the first day of the seventh month. Seventh month, you say? Yes, under the Biblical calendar reckoning, the first month was the spring month (the month of the Exodus from Egypt.) So… if the sabbath were to be celebrated as an annual occurrence on the seventh day of the year, it would come in the spring, about a week before Passover.
The idea of a holiday commemorating the birthday of the world is very late, rabbinic addition, not found in the Torah text.
I hope that’s reasonably conclusive.
Other interesting facts: the seven-day cycle was fairly common in the ancient Near East. In Mesopotamia, on certain months, the seventh, 14th, 21st, and 28th day were considered ill-omened and special ceremonies were used to drive away the bad spirits. Ancient Judaism transformed this into a weekly day of rest and sanctification.
The other holidays are all based on the lunar or solar calendar; the seven day week was the early interpretation of a lunar cycle as approximately 28 days.
