The Founders were adherents of natural rights theory. The U.S. Constitution's Bill of Rights was an add on, a year in, universally understood as an explicit statement of inalienable rights already implied and protected in the original constitution. It sought not to "grant" rights to U.S. citizens, but simply to clarify limitations on governmental power as a barrier to future tyranny.
Many of the Founders opposed the Bill of Rights, for fear it might suggest that the amendments "created" rights already, and again inalienably, held by free men, and potentially might suggest it was somehow a comprehensive list. To reach consensus the drafters included a nod to natural rights, the 9th Amendment: "The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people."
The right to keep and bear arms, for self defense, hunting, *and* as a guarantor against governmental oppression, was thus considered by the Founders as among the fundamental rights of man that no government can take away legitimately. Most state constitutions, at the time, provided similar language. Founders spoke outright about the armed citizenry as a guarantor that the U.S. federal government would not, and could not, oppress the States or the People.
Until the 14th amendment, and the Supreme Court invention of "incorporation", the Bill of Rights imposed no legal obligations upon the States. For example, at the time the Constitution was ratified, the State of Massachusetts *required* its citizens to participate in religious observance, in a way that rises easily, as we think of it today, to the level of an official state religion -- yet no one thought the Constitution's First Amendment posed any problem for Massachusetts.
After the Civil War and the ratification of the 14th Amendment, with the Civil War's renegade states denying rights to freed slaves, the Supreme Court began to "incorporate" the Bill of Rights into the 14th Amendment, and apply federal power to impose its enumerated rights.
Remarkably, it was not until 1925 that the Supreme Court applied the First Amendment to overturn state or local law restricting free speech or imposing religious duties. The Second Amendment was incorporated in the 21st Century.
In DC vs. Heller in 2008, the Court held 5-4 that yes, the 2nd Amendment guarantees an *individual right* to keep and bear arms, and that it was unconstitutional for Washington, D.C. to ban handgun ownership. That's now black letter Supreme Court precedent.
A decade before the case, btw, liberal lion Harvard constitutional law professor Lawrence Tribe acknowledged the individual right component of the 2nd Amendment is "unassailable". Justice Anton Scalia wrote extensively on the "militia" as meaning, unambiguously at the Founding, all able bodied men, not a creation of state governments.
It's is widely understood, however, that the U.S. will tip pretty drastically with the next one or two Supreme Court appointments, either to roll the 2nd Amendment forward to full incorporation parity with constitutional elements like the First Amendment, guaranteeing citizens, for example protection from blanket prohibitions on concealed carry; or to full curtailment, such that gun confiscation from law abiding citizens gets a full Supreme Court endorsement. The eldest, most infirm member of the court is far left activist (former head of the ACLU) Ruth Bader Ginsburg. Odds are, she'll be replaced by a Donald Trump appointment.
The origin of gun control in the U.S. was the so-called "Jim Crow" era, and sought above all else to keep guns from blacks fighting for civil rights -- and often for life itself -- amidst widespread KKK membership and an unholy alliance between the KKK and the Democratic Party that ruled the old South. There is perhaps no clearer case for the application of the 14th Amendment to guarantee natural rights. The history of the NRA and its black charters in the South is civil rights history.