Exactly.
The system they created was a citizen militia. This is NOT the system we have today...
True. Now we have a fair sized standing army augmented by the National Guard which is a form of select militia. And if we had a draft, not everyone would be called to serve or even at the least be trained.
Back then they wrote in the Militia Act of 1792 that each and every free able-bodied white male citizen of the respective States, resident therein, who is or shall be of age of eighteen years, and under the age of forty-five years (except as is herein after excepted) shall severally and respectively be enrolled in the militia...
That would be pretty much all of them, and they had to spend time training/drilling on a regular basis and purchase their own equipment, or at least some of it. And they got an idea of what war and the military was like which idea of necessity carried over into the rest of their lives including any public office they might eventually attain.
So you're correct when you write "This is NOT the system we have today..."
I would consider it an improvement if we returned to something closer to what the founder’s envisioned. And I am not referring to a draft, and I do mean most every citizen would own an M16 or equivalent (personally I’d go for a Sig SG550).