Where did I get the definition of the militia? The US Code: https://www.law.cornell.edu/uscode/text/10/246

As far as I know that’s been the definition at least since the 50s though I’m pretty sure at least the “able-bodied males 18-45” part has been around even longer

> Where did I get the definition of the militia? The US Code

You can't look to the US Code for definitions of terms in the Constitution; the US Code definition applies to the portion of the US Code that that definition is applicable to, but (except where the Constitution expressly gives Congress the power to define something) cannot define terms in the Constitution, otherwise, Congress could simply rewrite the Constitution by redefining the language used in it, and would never need to use the more difficult process of Constitutional Amendments.

As a general rule I agree, but in that case we’re limited to what the constitution says explicitly and what is says explicitly is that keeping and bearing arms is a right of “the People” which is a distinct group from “the States” and “the United States”. Further we know that the Militia is not the Army, nor the Navy, and that it too is also considered a separate group from “the people”.

It seems reasonable to conclude then that the right must be conferred to all the people because if they meant for it to be limited to the Militia they would have said “the right of the Militia to keep and bear arms shall not be infringed”