The concern about standing armies was addressed with financing limitations, two years.
"Militia" is the able-bodied public. The point of the 2nd amendment is to allow the people to persist in their ability to control, and if necessary, overthrow the government. The people had just thrown off the King, and were damn well determined to retain the ability to do so again.
I grew up in the UK. When I talk to family about the right to bear arms I also inject that it also includes the right to organize and train together, in military tactics, as an organized militia.
Jaws drop. I don’t believe many American’s realize how foreign of a concept our 2A is.