Point well taken. When one looks at some ancient buildings I wonder what we lost in time. The knowledge they had of astronomy is unexplainable. What all did the ancients know.
And that is only looking back 5000 years or so. What the ancients knew that we do not - mostly stuff we don’t want to know they knew, else the lie that life & progress is linear will evaporate.
Many ancient site have bits of glass in oval or round shapes - these are either discarded or classified as jewelry, but closer inspection reveals they are ground in plus or minus diopters or in other words they are lenses — something that is not permitted to exist until Galileo in the 16th century.
Many other bits of ancient knowledge disappeared when Julius Caesar accidentally fired the Library at Alexandria in 48 BC; a huge whopping amount was destroyed by the Islamic Varsity under Mohammad from 628-728 AD; and still more during the time of Girolamo Savonarola, 1452-1498 who loved to burn books.
Ancient knowledge which is ‘unexplained’ is just knowledge whose sources have been destroyed over the past 2000 years. Or knowledge that is not a product of modern, linear, logical, and reasoned thinking. Egyptian who lived during the Old Kingdom in Egypt thought symbolically - something that is nearly impossible for us today - a system of thought which is capable of producing things we have no basis to understand: the Giza complex as a unit, not separate ‘tombs’ for instance.
Now imagine some other race of beings on a planet within the habitable zone of a red dwarf sun - how do they think and what are the products of that thought - unimaginable.