No, it's not. There's no examples of people stopping mass shooters through guns, so your point of it keeping them safe it useless. There are exceptions, but if you own a gun, you're most likely to shoot one of your family members, so they're not making people safer.
I would say if you're a devout follower of any idealogy to the extent that you want to kill people, then yes, you shouldn't be able to purchase a gun, and that would come up in a background check.
The main, pragmatic reason was to fight against the British and slaves. Fighting "Tyranny" wasn't the main reason behind it. More importantly, the modernisation of weaponry is essential. At one point, we had the right to travel in whatever form we wished. Now that we have things like planes, we decided to increase regulations.,
Yes, it's been changed. Which shows it's not perfect, and the founding fathers knew this. Hence, to say that simply because it says something is a reason to follow it isn't a good arguement.
I'm not against guns because it's in the constitution. The fact that something is in the constitution isn't an arguement for or against it. There are many essential reasons for free speech, which there are not for guns.
Well, the right direction is banning MOST guns, but that's an unreasonable goal for a country like America. Reducing the amount of guns is a more realistic goal, and keeping them in safer hands. The fact that it violates the constitution isn't relevant unless you assume that it's a perfect document, which is clearly isn't.