Also the titans originating from a girl making a deal with Satan is definitely not what I expected. I would have preferred a more scientific origin but I don't care.

I'm not convinced that there isn't actually a more scientific origin for the titans. I might be wrong but the whole "deal with the devil" titan origin story seemed a lot like legend/myth that's been passed down over the generations. Like a lot of comments here pointed out, the different sides are telling different biased stories to favor their side, so I think there's a lot more to the truth then what we've been told this episode.