are there games that try to portray life and folklore of people I may not know about?

Kingdom Come: Deliverance might fit this. It’s set in 15th century Bohemia (modern day Czechia), and was designed with input from archaeologists and historians. That may present too much overlap with 15th century Bavaria, though. It’s an immersive sim with at least some jankiness, though I believe many bugs have been squashed since release. It can also be a bit tough in the early going as your character starts out pretty weak by design. Your character gets better at skills as you use them and the game starts to shine more once you’ve established some basic competency.

Are there games that play with this kind of meta mystery (I don’t know what word best describes it) where you have a glimpse that there’s something bigger behind the scenes?

I’d recommend There Is No Game: Wrong Dimension. Chock full of 4th wall breaks and meta commentary on games, game design and game development, plus lots of humour and a ton of heart. There is a bit of a mystery component as well. I’d recommend avoiding spoilers if at all possible, I went in blind and I think it made for a much better overall experience.