When you pick your theme in the beginning is there any significance other than the items you start with? I chose natural and now I regret it. Could I just remove all my natural stuff and replace it with another theme? Would that be the same thing?
If you plan to continue leveling up villagers, the camp will change anyway as you place different amenities. I don't think it matters for future aesthetics which theme you choose in the beginning as all the campsites are laid out the same way. It's only the amenities and which furnishings you choose to use that make the camp look a certain way.
Yes, you can add and/or remove things whenever you want. I don’t really see much of a point in even picking a theme apart from maybe making it feel more personal in the beginning *shrug*