From dating evidence found there, Gobekli Tepe (and presumably it’s equally massive sister site on a nearby Tepe) is more or less (within a century or so) contemporary with the cometary impacts that struck the northern hemisphere around 12,800 years ago.
Experts are pretty much in agreement, due to the sheer abundance of evidence such as you mentioned, glass and melted rock micro spherules and shocked nano-diamonds, and a relatively thin geological strata of burnt materials that date to the same period of 12,800 ya, a comet or more likely, a series of multiple comet impacts occurred in the Northern hemisphere, much of it striking the miles thick ice sheets covering much of the North at the time (leaving no craters as the 3 mile thick ice absorbed much of the energy and flash melted), causing massive and almost immediate worldwide floods and sea level rises.
This would have also had a devastating effect on the Atlantic ‘Drift’ current, aka North Atlantic current, due to billions of tonnes of fresh water mixing with the heavy saline water from the west.
Normally, the heavy salt water sinks to lower levels and create a conveyor belt effect which brings warmer waters towards Northern Europe…if this process is interrupted, as it seems to have been during the end of the last ice age and the start of the cold period of the Younger Dryas, it would probably be connected to these cataclysmic cometary impact events.
The monuments at Gobekli Tepe (used to be in Armenian territory just over 100 years ago, but was seized by Turkey during WW1.) may have been built around this tumultuous period in time, IMO probably just a matter of a few decades or so after the impacts.
It’s open as to why these monuments were built, used for 1000 years plus and then deliberately buried, but i like to imagine, mainly due to the anthropological nature of the main uprights together with all manner of animal figures carved upon those ‘Human’ uprights, is mean’t to convey to a warning of what happened to the future generations, and to tell of the worlds survivors coming together and erecting these many, many groups of intricately carved circles, one per group perhaps, who each were tasked with taking responsibility for their own particular circle, with the animals carved upon the stones being native or more abundant from where they originally came from.
I’d imagine for people who survived that cataclysm, there must have been profound shock at what had happened to the world they knew. How they’d lost everything, most of the people they knew and loved and how close we all came to being wiped out forever.
They’d certainly want to commemorate the event which almost killed everything completely, but certainly killed much of what any survivors once knew, and built a memorial as a warning for the future, to commemorate their dead and the destruction of their previous habitats and flora and fauna with respect to their own personal experience and the people, land and homes they’d lost…this is what i tend to think Gobekli Tepe actually is, and the same is probably true of the yet to be excavated sister site nearby.