From weeks in general: https://en.wikipedia.org/wiki/Week
The modern seven-day week can be traced back to the Babylonians, who used it within their calendar. Other ancient cultures had different week lengths, including ten in Egypt and an eight-day week for Etruscans.
There's probably a rabbit hole to go down to get into the mindset of who decided that a seven day week was a better system then what the neighbors are using. Babylonian astronomy and mathematics at the time likely played a role.
https://en.wikipedia.org/wiki/Babylonia
And overall there's a rich history to how we divide up the years in calendar reform.
https://en.wikipedia.org/wiki/Calendar_reform
Personally, I've fallen in love with the international fixed calendar. It proposes getting rid of the 30 days hath November nonsense and making all months 28 days. Take all the month-ends and combine them into a new month Sol, and since 28 × 13 is 364, create a new holiday called world day that is part of no week, no month, just doin' it's own thing. Add on a monthless leap day when needed and like magic, months are now a functional unit of measurement. 1 month = 28 days.