Personally, I think we would have been better off without the 2nd amendment, and the framers of the constitution may not have foreseen the role it has come to play in politics (if so, it would be far from the only case), but I cannot find much ambiguity in it.
Also there is no "no sanding Army" requirement. There is only a requirement that the army can only be funded for 2 years ahead, presumably to require ongoing consent from Legislature, to prevent a Chancellor Hitler-type situation or a President becoming King by getting a huge multi year funding and then turning against the future Legislature and the country.
And the War of 1812 taught President Madison the danger of being under militarized and over-reliant on militias.
Many Founders believed a standing army to be an inherently corrupting force (if you have a warrior class, sooner or later they will make you go to war) and thought America would be better without one. Whether or not that could have been true in the abstract became irrelevant because the need to perpetually defend territory meant that there was never an opportunity to disband the Continental Army.
The Second Amemdent's in there because without it, the states wouldn't have been willing to ratify a Constitution that allowed the federal government to take their guns away. After all, they had just won a war against a monarch an ocean away; they weren't about to give their power of defense to an executive half a continent away. Remember, there was no guarantee a Constitution was going to happen at all; quite a few compromises and curveballs in that document are there because every single state had the option of rejecting the whole thing and being their own country. Many Founding Fathers envisioned defense of the US would look like individual states generally handling their own affairs, and a national army only being mobilized in the event of a national threat (however, practically speaking, that didn't come to pass... No sooner was the Constitution ratified than Washington led the Continental Army to force the citizens of western Pennsylvania to pay federal taxes).
Gun regulation was properly recognized as a state authority for most of the country's history prior to the Civil War and varied wildly from state to state, with many being significantly more restrictive than modern law. It's only with the passage of the Fourteenth Amendment (and the Due Process clause, "No State shall make or enforce any law which shall abridge the privileges or immunities of citizens of the United States; nor shall any State deprive any person of life, liberty, or property, without due process of law") that the Second Amendment ties the hands of state governments in the same way it tied the hands of the federal government. This restriction has been re-interpreted over the decades, but broadly speaking that's how we got from a 1700s Philadelphia that banned gun ownership for some immigrants to the modern interpretation where even tracking who owns a firearm might be considered an abridgment of the right of ownership.
One advantage the chosen approach has is, in a sense, interpretive simplicity, even though in practice it strips much authority from the states and moves it up to the federal level.
That pretty seriously overstates the case: The American Revolution started out that way, but as time went on, the Continental Army acquired serious artillery and became reasonably professional — thanks largely to Henry Knox; Baron von Steuben; and the Marquis de La Fayette — and the decisive factor at Yorktown was the intervention of a French naval squadron and expeditionary force.
https://en.wikipedia.org/wiki/Continental_Army
https://www.historynet.com/arming-revolution-continental-arm...