edit- follow up question
“a well regulated militia”. since the amendment was passed, and since the US has a military, has there even been a militia? would you trust your random neighbours loading up and marching against something? or would you expect law enforcement to crush it?
seems like the amendment has become “the locals can have guns and murder each other”. Nothing to with a “militia”; or defending your country.
You have to remember that some of the colonies were over a century old and suffered under most of that time under benign neglect. The colonists were responsible for a lot, including some military self defense.
Militias were the primary form of that self defense, locally raised military units under local control including self selection of officers. If a colony needed to raise an army, it would mostly get these militia units pre-assembled. A lot of the American Revolution was fought with these units. These units also generally held loyalty to the colonies/states they were mustered in, not a higher entity.
The founding fathers may have included protections for individual armament, but a lot of the intent was to ensure that the new states could independently raise armies of militias in the same manner they did as colonies.
The Bill of Rights was also only intended for the federal government. At the time of its adoption, the Bill of Rights didn’t bind the states; individual states could regulate the formation of militias as the ownership of guns. This was just the federal government binding itself from doing so.