The Constitution is different from ordinary legislation because it is harder to change, and was designed to be so. When you say “we would still see farther than they did, standing on their shoulders,” you miss the point that we do not have their real-world experience of being repressed by their own Government, the so-called “tyranny of King George”. The need for citizens to bear arms was to prevent a home-grown tyranny from replacing the British one: the Constitution was designed to have decentralised power in the States, with their own armed citizenry to keep the State governments honest. The Federal power grab by President Lincoln known today as the Civil War removed that decentralisation by removing most State powers, and centralising them federally.
If you want to understand whether the founders wanted the citizens to have access to a particular style of weapon, you must first ask “Do Government forces have access to these weapons?” Since they intended US citizens to be capable of taking on the US Army if it were controlled by a Tyrant, then the answer is clear: Automatic weapons, grenade launchers, anti-tank and anti-aircraft weapons: all would have been applauded by the Founders as a counterbalance to the overweening power of big government.
I don’t say this is a reasonable right today, but if you want to understand the intent of the Second Amendment, I have just explained it to you.