Guns have only one purpose though, to injure or kill whether a human or an animal. No other thing you mentioned is single purpose like that.
Plenty of countries survive without guns so you can either argue that Americans are extremely violent or the police is completely incompetent. Yes, 3D printing is a way around it but if the penalties are extreme, people will think twice about it. The alternative of "let's just arm everyone just in case" is a terrible idea.
Yes, guns are designed to kill, but they actually have a secondary purpose. As with nuclear weapons, they act as a very strong deterrent and can actually prevent violent crime from happening. Many videos on Youtube where a gun was used to de-escalate a potentially violent situation. I think there are legitimate uses for guns even when killing is involved. I believe that people have a right to self-defense. If a bad guy is killed by a good guy defending him/herself or others, I have no problem with that. It's unfortunate, but I'd rather see the bad guy die than the good.
I would argue that certain cultures in America are way more violent than what you'll find in other developed countries. They tend to be clustered in areas where you don't want to find yourself at 11 PM on a Friday night.
I wish we could just get rid of all the guns, nuclear weapons, and speed bumps. However, if the US government tried to round up and destroy all guns, they would only get guns from the good people. Bad people will never give up their guns. So in that case, we'd end up with a higher percentage of guns in the hands of bad people.