In the present day, civilians own tanks, cannons, rocket launchers, grenades, machine guns, explosives, etc. This has largely been the case for 200 plus years. If we ignore the some 200 years of jurisprudence supporting that ownership, then what?
Then we can reinterpret it to mean "human arms", as opposed to legs. I mean, the courts have the final say in what the US Constitution says, so just rattling off "the constitution says X!!!" like it means one thing but ignoring the years and years of case law meaning something else (and what's actually enforced) is just being naive.