If it were self-explanatory there wouldn't have been court cases to decide what it meant.
Actually, come to think of it, before 2008, there was really only one Supreme Court case that ever truly made a judgment regarding the 2nd Amendment's relationship to personal firearms, and that was the United States v Miller case of 1939.
It wasn't until 2008 that the Courts suggested that the 2nd Amendment protected personal firearms ownership for anything other than militia service. My position, in case you haven't figured it out, is that the Court replaced originalism with strict textualism.
Ironically, three of the justices who were around to decide that case (Heller) on the basis of textualism, now appear likely to use originalism to argue that Trump should remain on the ballot in all 50 states.