At the very bottom of physics, if we ever reach it with our observations and theories, there will be something that simply is, and is not explained by the interactions of some sub-system. The foundational elements of physics are probably non-conscious (assuming the currently known particles and fields are indeed non-conscious).

What grounds do we have for asserting as certain that consciousness is not a foundational thing-that-simply-is, but must definitely be composed from sub-systems that are themselves non-conscious?