"...the creation of Adam or his departure from Eden was around 3983 BC."
...therefore might I suggest...
3983 BCE + 2021 CE = 6004
This would suggest the 6000 year plan of God for man is possibly over now and prophetically "Are we possibly 4 years into the Millennium and didn't know it?"
A possible problem with the 6000 year plan of God in North America.
How old are the Clovis sites in North America?
While Clovis sites are found throughout North America, the technology only lasted for a brief period of time. The dates of Clovis vary from region to region. In the American west, Clovis sites range in age from 13,400-12,800 calendar years ago BP , and in the east, from 12,800-12,500 BP.
East Wenatchee, Washington Clovis points in situ
Closer to Biblical home base...
JERICHO ISRAEL
Jericho Israel challenges the commonly held belief among scholars and historians that the oldest civilizations in the world belong to Egypt and Mesopotamia. Excavations over the last 100 years have produced evidence of habitation off and on since the Mesolithic Age. Archaeologists date excavated remains anywhere from 9,000 B.C. to 7,500 B.C., making Jericho Israel the oldest city in the world, and, arguably, the world's oldest civilization.