My understanding is the federal laws only "override" state laws in the context of the "enumerated powers" in the constitution, which are supposed to be few and

My understanding is the federal laws only "override" state laws in the context of the "enumerated powers" in the constitution, which are supposed to be few and narrow. This is why no State can pass a "law" that would allow you to enslave others or violate their other rights granted by those "enumerated powers" of the federal government.