So, to put it simply, without complicating things: these [Drempelplatten] inside should not have any structural function. You can remove them as long as you leave the posts standing. I mean, I have seen something like this before, where you create floor space behind the posts, then nicely varnish the posts. You can put a dresser, a bed, or something else between them to create space. I am a fan of visual spaces through the use of sloping ceilings or [Bodenfenster] and the view behind the furniture placed in front. Because even if you can't really walk on these areas, they make the rooms look visually bigger.
Best start in one room and let the result affect you. Don’t forget photos before and after.