" If a modern human went back in time to the time these legends were written, if they were able to communicate and if they didn't give everybody some modern-day pathogen that's lethal to the lot of them, how are you going to communicate the size of just our solar system to anybody from that era in any functional way? You'd almost have to introduce some hackneyed number like 5,000 years for it to be understandable."
Agreed. In order to grasp both the size and time aspects of the universe would require advanced mathematical understanding.
However, even today journalists are advised to avoid statements like
"30% of the population" and instead say
"three people out of ten"
Depressing isn't it?