The right to keep and bear arms preceded the U.S. Constitution, as our Founding Fathers “propounded” the right but did not create it. They enshrined it via the Bill of Rights, all the while knowing the origin of the right itself was to be found in “the Laws of Nature and of Nature’s God.”
Thomas Jefferson learned these things from Common Law commentators like William Blackstone. It was Blackstone who so clearly showed that the right to be armed was a natural right “that common law might propound but did not create and could not revoke.”
Jefferson was by no means alone. In her book To Keep and Bear Arms: The Origins of an Anglo-American Right, Joyce Lee Malcolm shows that the Founders and their contemporaries were of such a mind that some of them did not even push for a Bill of Rights: they saw no need to do so because the preexistence of the right to keep and bear arms was so obvious to them.