@Potatogod me too but the story was short so it felt wrong to discuss in the first chapter... Well, their bad for not hiding it properly XP
My guess, people messed up with genetics jurasik park style so they got wiped out Planets of the Apes style and this is what's left of humanity... But, I think Dr Stone would have some criticism for this manga- ah wait no, we don't know how long has it been since modern civilization died out.
@bluedudu its pretty obvious the tower was some godly artifact (how else would the glasses be in working condition after all that time), clearly whoever ventured in there would find exactly the kind of item to grant their wish (like if other girl hadn't wished for a friend/companionship, she would probably have found some sci-fi healing station that can even restore lost limbs). Particularly as the ad said they would fulfill any wish, which is something no mall can possibly claim, its probably that deity's message.
tl;dr - Too much of a coincidence. The god myth about the tower must have been true in-universe (although doesnt have to be a god. Any kind of seemingly omnipotent being works).
edit: another thing to note was how there was a mention of some being appearing at moment of birth, genetically enhancing ppl.
WOW man, it actually finishes in 3 more chapters WTF MAN how is this shit ONLY 5 chapters long? this series is interesting and has potential OTL fucking feelsbadman
MC had eye problems and the setting is in a stone-age kind of era. But even so... doesn't explain the dinosaurs though.
Perhaps an experiment went wrong and past and present ended up mixed?
This is the sort of story that has a nice mystery to it.