Yes. Copy will only get what was selected, dropping all the rest.
Edit: I took a look at the model. I didn’t find any issues with errant leader text or entities far from the origin, but for some reason the view’s camera has gone off to beyond Jupiter and the model is too small to see from such a distance. The green is the ground plane, which shows because it is infinite. The copy-paste technique makes SketchUp reset the camera, so that is one way to repair the view as well as to purge unused content.
While looking, I noticed some other problems. To help with better modeling in the future:
Just two components, the TOTO showers and the chairs, contribute over 264000 of the model’s 294777 edges. They were no doubt downloaded from the 3D Warehouse, and are wildly over-detailed for what they contribute to the model! This is a common issue with things found in the 3d Warehouse. They may be ok as detailed standalone models, but will rapidly bloat a larger model if you embed them there. Always download from the 3DW to a separate model and check for appropriate detail before adding a component into your model. If you won’t be able to see the details in the normal use of your model, there is no reason to include them! You could make your model much more manageable by replacing those components with something simpler.
The large window component has two levels of unnecessary nesting; all the geometry is in the deepest entity in the nest. You can explode two levels with no bad consequences. Furthermore, all those edges and faces are associated with the Library 1st Floor layer. All edges and faces should be drawn on and associated with Layer0 and only their component or group should be associated with another layer.