Have you been told yet that all primitives, (faces, edges, curves, circles, polygons, etc.) need to always be assigned to “Layer0” ?
Groups and Component Instances can be assigned to other layers for controlling visibility. But the entities within their entities collection(s) are still assigned to “Layer0”.
In SketchUp, layers are a visibility property. They are not a collection of entities. Entities are not “ON” a layer.
Layers do not prevent entities from interacting / intersecting, etc. This is what Groups or Components are for.