All we can do is date the cuts of the blocks and they all belong to a civilization older than sumer. Somehow sumer is the oldest civilization according to official history books.
They are not the oldest exactly. Just one of the older ones we know more about because of how much of their writings survived. We think human civilisation started about 12000 years ago
You know nothing. Obviously. These civilization are completely absent of history books and we officially know nothing about them beside the massive blocks remaining.
While history is one of my least studied subjects I know that they do not hide knowledge of ancient civilizations. They just admit to not knowing much about them.