“Saturn’s rings require at least a 15-mm-diameter telescope[133] to resolve and thus were not known to exist until Galileo first saw them in 1610.”
https://en.wikipedia.org/wiki/Saturn#European_observations_(17th–19th_centuries)
Crystal lenses were ground and used during the Egyptian Old Kingdom - they are ground to optical diopters for eyeglasses - the kind held on a short stick. These lens are found in many Egyptian displays labeled as jewelry - which they clearly are not. There are records of long distance (beyond normal vision range) observations, as well as descriptions of the tubes (a now extinct plant) the lens were mounted in.
They were no more ignorant of the stars and planets as any 20th century person - perhaps more so.
As for the Saturn Death Cult - poppycock - as far as the Egyptian Old Kingdom goes. People in those days thought differently than we do for starters - we think linearly; they thought symbolically. We see a figure with an animal head and immediately associate it with some god; they saw the forces and attributes the figure represented in their daily lives.
In those times, life was the DAILY preparation for what happens to a person after the body dies. Will they know enough to pass all the tests after death and journey to the River of Stars (the Milky Way) and arrive in the Land of the Gods (somewhere in the constellation of Orion). Or would they fail and be beheaded and fed to the Eater of Souls?
BTW: there was no word for religion in ancient Egyptian.
Those ancient religions were all astral in nature. Primitive people seeking to devise an astral religion today would end up worshiping the sun and the moon. But the two chieftain gods of every one of those old religious systems were the two dwarf stars or former dwarf stars, Jupiter and Saturn, and particularly Saturn. Vestiges of that old reality are all around us. We still call our sabbath "Saturn's day"; the chief Roman religious festival was "Saturnalia"; Vergil describes (Aeneid) Rome being built over the ruins of an older city called "Saturnia".
Plato consistently refers to antediluvians as "nurselings of Cronos(Saturn)"; Hesiod and Ovid describe history as a golden age during which Saturn/Cronos was the "king of heaven", followed by the great flood, and then a silver age when Zeus/Jupiter was "king of heaven", followed by the Trojan war and then the present iron age.
In the same language, our sun is the "king of heaven now".
Given what they teach in schools as to how our system formed up, you'd expect the spin axes of the bodies in our system to all be roughly perpendicular to the plane of the system. The sun, Jupiter, and Mercury all do look sort of like that, spin axes less than ten degrees. There are two or three bodies with oddball axis tilts, but then the four remaining bodies, Saturn, Neptune, Earth, and Mars all have the same rough 26-degree tilt, indicating that they were all captured as a group and probably very recently. That would account for the recent megafauna die-out conventionally placed around 12,000 years ago as well as the flood and some of the other worldwide disasters mentioned in ancient literature.
People steeped in public-school cosmology could think of Troy McLachlan's book as a ten-dollar education upgrade.