I think you may have misunderstood. The aliens were interacting with humans literally since our inception. What we recognize as "civilization" was rebooted by them in Sumer after the Great Flood. Then a significant change in the relationship between humans and the aliens and that state of affairs on Earth came along much later, around 600BC. We must carefully separate all these events and understand the status quo before and after each.
I think you may have misunderstood. The aliens were interacting with humans literally since our inception. What we recognize as "civilization" was rebooted by them in Sumer after the Great Flood. Then a significant change in the relationship between humans and the aliens and that state of affairs on Earth came along much later, around 600BC. We must carefully separate all these events and understand the status quo before and after each.