Static worlds tend to feel very lonely, you can take a look at WindShake to add some movement into your trees and grass parts, you might also want to look at adding some mild environmental conditions (e.g. light snowfall, just move a large intangible invisible part to the camera’s position with a snow particle emitter as a simple solution, or look at buildthomas’ rain module and see if you can tweak the images and parameters to look more like snow if you need roof occlusion). If it suits your world, you could think about NPCs, distant birds in the sky, and environmental sounds (e.g. occasional bird sounds, wind, trees rustling), audio does a lot of heavy lifting and we just never notice it until it’s missing.
As far as content goes, I think you’ve done sufficient decorating. You probably just need to breathe some life into it.