Who created the calendar and when?

In the Bronze age in 3100 B.C, The Sumerians in Mesopotamia created the first calendar and divided it into 12 lunar months (That means moon) each having 29 or 30 days, It was different than calendars we have now... only it does not seem like it. Timekeeping started way back in the Neolithic period but actual calendars were created in the Bronze age.

The Who can't be answered other than "Hunter Gatherer Tribes in Scotland" the when about 10,000 years ago

British archaeology experts have discovered what they believe to be the world's oldest 'calendar', created by hunter-gatherer societies and dating back to around 8,000 BC.

The evidence suggests that hunter gatherer societies in Scotland had both the need and sophistication to track time across the years, to correct for seasonal drift of the lunar year and that this occurred nearly 5,000 years before the first formal calendars known in the Near East.

https://phys.org/news/2013-07-world-oldest-calendar.html