Yeah, I've heard this theory before, and it kinda makes sense. Except that there are other countries (most of the Anglosphere, including the UK) that also had slavery, (and/or have confronting relationships with their indigenous population), and don't feel that same fear.

Is there something unique about the USA's history with slavery that would cause this?

Its about owning a farm in the middle of nowhere not slavery. It really is not that hard to understand that people have different worries back when the second amendment was written when the nearest town for protection is weeks away and not hours.

Yeah, interesting. But we don't see the same reaction with Aussie farmers. I mean, most of them do own guns, but that's more about the wildlife...

It does not matter what threat its about protecting or even if its that likely to happen. Its human nature to have things to protection youself and things you care about. Like insurance you never need it until you do but then its too late.

“God created man. Sam Colt made them equal.”

And yet, that's not true in any other country. So I doubt it's human nature.

Other countries have locks and self defense weapons even firearms. marshal arts have existed in all cultures world wide.

Denying self defense isn't a core part of human history and desire for political reasons is very unscientific.

Think of the other side of the coin. Through history the first thing slaves are denied are weapons. And there is many countries that allow weapons at home, US, Mexico, Latin America....