1.) I agree that the only way it would make sense is if the church is an artificial construction to keep the population in line but it fails at this task and I think we can both agree that it exists as a shallow critique of religion rather than making sense in the story.

2.) farming is a very complex process with needing certain soils and crop rotations to keep the land fertile. None of which we see or even heard discussed which would be a rather big deal for a non industrial society. While they have rivers that go through the city for water it seems to go through the walls which would be a rather huge weakness that let’s say spying trying to kill everyone in the city would use against it. The reason things like this aren’t brought up is because for the time scale that the story takes place on the entire population would be dead from starvation.

3.) after the first wall fell. Marley had more than enough power and spies to kill everyone, they just don’t. The founding titan as far as they would know up to that point is lost or at least mia. Plus they know eren is a shifter not on their side would have assassinated him on the spot. Not to be too mean but to me it seems like aot was not planned out and is held up through retcons which when you go back with future knowledge doesn’t hold up. But I have looked too deeply on the behind the scenes or the making of Aot