I see the data you’ve linked, but find it fascinating what the parent comment is implying.

OP is asking: “guns have been around for so long, why are mass shootings more common only recently?”

Parent comment’s answer is “total murder rates used to be higher before and the rate is now less than what it used to be before”

Even looking at your homocide data, what does that mean? Why have mass shootings increased?

And the further question that brings to my mind is: are people putting together these 2 pieces of unrelated data, to draw the conclusions that support their own bias? Great that overall murder rates are down compared to the 70s and 80s…but that doesn’t mean the country doesn’t have a gun problem or that mass shootings are unnecessary and avoidable deaths and a sign of some underlying unhealthiness in a community.