The history explains the oddness a bit. It was originally loosely based on Pennsylvania and Massachusetts Bill of Rights which said:
> "That the people have a right to bear arms for the defence of themselves and the state; and as standing armies in the time of peace are dangerous to liberty, they ought not to be kept up; And that the military should be kept under strict subordination to, and governed by, the civil power."
I think that's very clear. They were deeply concerned about the threat a standing army posed, and wanted the militias to act as a balance. Based loosely on that Madison's first draft then said:
> "The right of the people to keep and bear arms shall not be infringed; a well armed and well regulated militia being the best security of a free country: but no person religiously scrupulous of bearing arms shall be compelled to render military service in person."
Again, more comprehensible than what we have today. Still a bit oddly phrased, but it's clear that the right can't be infringed BECAUSE we need a well regulated militia.
Then, after much debate and quibbling over the exact phrasing and in regard to religious objectors the committee submitted this to the senate:
> "A well regulated militia, composed of the body of the People, being the best security of a free State, the right of the People to keep and bear arms, shall not be infringed, but no one religiously scrupulous of bearing arms, shall be compelled to render military service in person."
As you can see, even this version was a more complete thought, and made it very clear what the purpose of those arms actually was.
However, the senate then did the final butchery, that resulted in the version we have today and because unscrupulous people have exploited it's vagueness, school children can't be safe:
> A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.
Reference:
https://constitution.congress.gov/browse/essay/amdt2-2/ALDE_...
To me, the real bitch is that the original purpose (to serve as a balance against the standing army) is completely null. There is no militia, or even professionally trained army strong enough to stand against the permanent army the founding fathers didn't even want us to have. Thermonuclear warheads and fighter jets didn't exist back then.
Even though the NRA likes to claim the "militia" means every American, that is NOT what Madison and the others meant by it. It's made clear in the Federalist papers, and even if it were what the founding fathers meant not even the NRA seems to be taking the stance that since the "miltia" means "Everyone" then "Everyone" can own thermonuclear warheads.
The second amendment has been wrongfully interpreted, and it's killing people.