And they are totally wrong because there were all sorts of machine guns and powerful cannons available in those days, even some used in the Revolutionary war.

Projectile weapons have been improving throughout history, it’s silly to assume the Founders weren’t well aware of that. I mean, there were medieval weapons that were pretty devastating by even today’s standards and the first amendment makes no mention of that. These were enlightenment thinkers well versed in the history of governments and technological progress.

The 2nd amendment is a principle meant to transcend all time and cultures. The people have a fundamental right to defend their rights.

I mean, we already know that the first amendment doesn't (and should not) apply to some forms of speech; slander, libel and incitement to violence are all things that we (as a society) have decided are forms of speech that should be regulated.

The first amendment isn’t intended for physical speech. It exists to protect opinions and ideas. It’s for this reason lots of non-verbal “speech” is protected under the first amendment, like online posts and flag burning.

Threatening violence or slander has nothing to do with the first amendment.