I am sharing one such example from ved which proves ancient people knew a lot more than what we think they knew.
Above image says -
"The shine of moon is due to sun light. (3)
Earth gets rain due to sun (sun influences wind)"
It clearly shows they knew about astronomy enough to know Moon doesn't has its own light. Vedas were written in text form for almost 5000 years ago and were present in oral tradition for unknown time.