Thank you for taking the time to play.
The goal of the game is not to be simple but rather to be believable and to immerse the player in its world.
After you beat the signpost puzzle the game never again locks your progress behind having to solve anything. You actually went through the entire content progression without any issues which was more important as feedback. It's interesting you mentioned Obra Dinn since it works in the same way -- You can get through that entire game without solving a single death but then you lose the game at the end. I have watched people go through the entirety of Obra Dinn while only solving 10 fates so this is not new to me.
I've noticed that players have a tendency not to engage with the Case Notebook too much. I think that's on me and I will try to make it more engaging and compelling to solve things there, since that is the main gameplay focus, but at the same time different players play games in different ways and I have started to be more aware which types of players are my target audience and which types will never become complex puzzle fans no matter what I change.
Good luck on releasing Little Locked Rooms.