Thanks for writing such extended feedback - I'll try and address all of your points, but don't hesitate to ask for further clarification if I haven't given enough detail.
To begin, I can definitely see how the opening could come across as too heavy with dry exposition and references with little context - however, that's also due to most of the setup being frontloaded; since the 'normal' order of things disintegrates very early on, so there's not as much opportunity to spread that background through the game in a place where certain characters can be seen interacting instead of it just being described second-hand.
Most of the introductions are taken care of in the demo, so hopefully you'll find the full game to move at a more streamlined pace.
I haven't heard that issue with the courtyard mentioned elsewhere, so I'll be sure to see what could be causing it - thanks for reporting it, even "obvious" seeming errors can be missed.
Regarding the chimera battle - you're right in seeing it as unwinnable, as like all chimera encounters in the full game, it's not possible to defeat it. To progress to the last scene of the demo, you have to choose the "submit" option that's added to the game over menu when you die a second time against it.
The full game's chimera encounters progress normally from dying once, but the additional menu part for the first is intended to play off the frustration of repeating boss battles with unskippable cutscenes.