That's cool. I should add Hanaharu Naruko's page. It's pretty uncommon that these people work on hentai before on anime and manga. The author of Azumanga Daioh, Kiyohiko Azuma, worked on Inma no Ranbu (hentai) using a pen name before working on Azumanga Daioh. Acura Max and I found a seiyuu who drew hentai manga, Haruki.
It's awesome to see you in the discussion.
Maybe your time travel hypothesis is not wrong. Auron570 brought up the Ice Age thing. Ledo thought Earth was inhabitable for freezing. It might be time travel or a conspiracy (see that Robotics;Notes reference I pulled!)
Spoilers for Episode 3 (Don't Read)
I like the episode especially the pirate Empress, Lukkage. I thought her slaves were victims, but they were her bodyguards. That was a big surprise.
Fans talk about a possible romance element in Gen Urobuchi's work. I thought there was romance in Fate Zero, but I guess they didn't count Kiritsugu and Iris because they're married or so.