I was only responding to the “charge” that the bible says the earth is flat. It says no such thing, and ancient people did know the world was round.
What you said, specifically, is “All ancient civilizations knew the work was round.” That is not the case, as any historian will tell you. I linked you to university sources in the prior response which show that ancient Egypt and Babylon, which neighbored Israel, Palestine, Jerusalem, etc. had flat earth cosmologies at the time the Torah was written. This influenced the cosmology found in the Torah, aka the Old Testament.
Probably your strong feeling that you’ve seen legitimate sources agreeing with you owes to common articles about medieval Europeans mostly being aware of Earth’s true shape. However, medieval Europeans were not “all ancient civilizations”, nor were they the authors of the Bible.
More resources for you: