With the weapons available in 1776, a single individual gained almost nothing by posession of a firearm, in terms of self defence.
If you were set upon by a mob, and had an eighteenth century pistol or long gun, then (if it was already loaded, and if the powder was still in good condition, and if the flint or pyrite wasn't excessively worn), you might kill or injure one of your assailants, and if those assailants were concerned that the sound of the shot might summon reinforcements, or were not expecting any resistance, the shot might scare them away.
As an individual, a far better defensive weapon choice would be a sword, or even a dagger.
C18th firearms were only really useful as a collective defense - you needed at least a few armed men to put up a continuous fire, with each taking turns to fire while his allies reloaded.
The idea that a lone gunman could achieve anything more than a single kill, before being rushed and defeated, was unthinkable to anyone in the C18th - So they didn't think about it.
Multi-shot guns, or even breech loading guns able to be re-loaded quickly, simply didn't exist, so legislating for the use of firearms by individuals (not acting in concert with others in a well-regulated fashion) would have been senseless, and suggesting that there was intent to formulate such legislation (whether as a constitutional right or otherwise) is a foolish example of presentism - the ascribing to historical figures knowledge that simply did not exist in their time.
The rugged self-defense by a single armed individual of his person, his family, his country, and his very freedom, is a 1930s myth, based on a Hollywood mangling of 1830s history (when Colt's revolver suddenly made a lone gunman into a practical possibility).
The authors of the Second Amendment were absolutely certain not to be thinking about this myth from 160 years in their future, based on an invention sixty years in the future, when they drafted that part of the Bill of Rights.