Militias are creatures of the individual States and local jurisdictions. When Washington was in command during the Revolution, one of his big complaints was that his troops that came from the State were poorly trained and poorly organized. He described their uniforms as little more than "rags". Sanitation and disease were rampant. One of the reasons that von Steuben was brought in was to try to make a military out of disorganized, poorly trained group of militias.
When the Constitution was passed, the Federal Government was given the ability to nationalize the State Militias when needed. This was formalized in
Militia Acts. The big problem during this time was that the Federal Government had no money, so they were very dependent upon the States to police themselves.
The public wasn't in favor of a national, permanent Army (it's fair to say that the public didn't want to pay for a permanent Army with taxes, either). If you read the documents from this period, you'll also see that most of these Militias didn't have guns, so if the soldiers didn't bring their gun with them, they usually went without a weapon.
So, if we want to be "Originalists", then we have to also view the DIY element of Militias in the early United States. Now that we have a professional, standing and permanent national military, we also have to question this idea that we're all supposed to be armed to protect ourselves from a tyrannical Federal government. The history really doesn't pan out on this reasoning.
Fun Fact: rumors surrounded von Steuben and his dalliances with men. He could well have been America's first gay man in the Military.