To a primitive person 4 or 5 millinia ago, the sun and the moon would appear as "lights". There is no suggestion that they thought of them as different things, one a nuclear furnace and one a lump of gray rock reflecting the light from that furnace. There was one light and one mirror. They had no idea that they were spheres or that they were anything but bright spots in the nightime (Three Dog Night). That they were "lights" was easily observable with the naked eye.
Five millennia ago would put us in Genesis chapter 11, around the time of the Tower of Babel. I believe that there were people there who actually knew what the stars were.
Adam walked and talked with the Creator.
“Lord, what are those lights in the sky?”
“Well, let me tell you, Adam. On the fourth day, two days before I made you and the Misses, I created a big ball of burning gases and set it at just the right distance from the earth — any closer and you’d burn up, and any further and you’d freeze to death. I was thinking about you, Adam. And then I knew that you and your sweetheart would need something to gawk at in the night, sitting on the lawn by that Tigris River, so I put another ball of dirt up there that could reflect the light of the sun as the earth rotated, putting you on the opposite side. Ain’t it romantic, Adam?”
He passed that knowledge to his children (perhaps more than a hundred of them in 930 years), and to his grandchildren, and to his great grandchildren, and to his great-greatgrandchildren, and to his great-great-great grandchildren, and so forth (930 years old!) And who told their children.
The knowledge of God wasn’t passed by men who lived only 70 or 80 years, but by men who lived almost a millennia in good health (before the flood), and saw a dozen or more generations of their own seed come along.
Adam was probably still alive within 120 years from Noah getting on the ark.
And I believe Noah knew what a star was, and taught Shem, Ham, and Jepeth, and his grandchildren, and great grandchildren, and great-greatgrandchildren, ect.
Noah’s son, Shem, was probably still living in Abraham’s day.