The motivations underlying 2A are:

Protection

Participation in military / national defense

Resistance of tyrannical government

Hunting

Depending upon whether or not you think the Constitution is a living document, a modern reading of 2A could reasonably include things like explosives, drones, radar, etc., but maybe exclude things like nukes, fighter jets, biochemical weapons, other purely offensive things. I'm very pro-gun regulation, but I think this would be a fine reading as long as we're doing the same thing across the Constitution, i.e. substantive due process.

But while conservatives love modern readings of 2A, they deny modern readings of anything else. So they have to find some way to fit their desired outcomes into originals/textualism, leading to absurd dilemmas like "either the founders meant muskets or they meant nukes", or tortured standards like scanning all firearm or self-defense laws in effect around the late 18th century to discern intent, which predictably do not emerge from consistent foundational principles because their authorship is scattered across space and time and thus really are no help... unless of course you cherry pick shamelessly.

I think that’s the only logical conclusion of the “shall not be infringed” absolutists. They shy away from admitting it, though.

“Oh, those aren’t arms. They’re, uh, destructive devices!”

It's an interesting legal question. Around the time that the US Constitution was written there were private citizens who owned artillery pieces and even entire warships.

It ought to.

If you can afford either of those you have enough invested in the system that you probably won't use it lightly and if you don't you should and that's kind of the system's problem.