That’s not true. They knew very much about the regularity of the changing positions of the heavenly bodies. They knew certain good times in the day or month or year to perform various practical tasks like expecting the sunrise soon bc of the bright morning star or telling time with sundial or when to hunt vs gather for moon phases or when to plant and harvest and expect floods or rainy seasons etc. They knew how to navigate.

Plus we knew God created it all because He told us quite some time ago.