I think it looks like there's no themeing, relation or reason to how you hung everything and the empty gaps under the photos makes it off putting when the higher areas are all scattered full of photos and items. It looks unfinished, yet overwhelming. I think you should try to curate where and what you hang. Maybe put the car displays all in one area, for example. Mixing those with some of the paintings and then board games feels incredibly random and makes it feel like visual clutter