How exactly do you guys want to “go back to Earth”? You say you don’t like sci-fi but then suggest time travel..uh?
Going back to ancient ages will never work. Why? Let’s go with an example: how would that age’s units be? Stronger than in space ages? How exactly would an “Aztec warrior” (just an example) be stronger than a tank in space age Venus (or whatever, pick one)? And what about the buildings? What would they be made of? You have modern, good looking (imo) buildings right now. Would you start building houses of wood? When you have the technology to time travel? I’m sorry but it just seems way too forced to me.
The only way I can see on how to go back to a regular planet (e.g Earth) would be if, after the solar system, we could be able to colonise some planet on another system and, for some reason, you don’t have the materials in that planet to produce good, modern stuff, so you gotta resort to go along the way since the beginning: conquering land, then oceans, then skies, etc… but then you’d, once again, run out of stuff to do and we would come back right to this point.
This is a hot topic but highly complex in my opinion. Would love to debate this with someone, though