I knew you'd say that. I heard you. I am comparing our culture today to what I remember as a kid and what other posters here remember about bringing their guns to school for rifle practice after school and such. A school shooting was completely undreamed of. A mass shooting was unheard of until the UT Austin Clock Tower shooting in 1966. Gunned down a flock of student nurses, if I remember right. It was 18 years until the next one, at a McDonalds in California. Then they start happening with more regularity, every couple of years. Now they're happening every year or more than once a year. This year will probably be a red letter year, considering we've already had two and it's not even June yet.
You're right that the homicide rate now is comparable to when I started grade school. Where, then, are these mass shootings coming from? That is not a figment of my imagination. And they were not around in 1960.
It's not a figment of your imagination - the error, so to speak, in your reasoning is that you're using anecdotes and deciding that culture as a whole behaves this way.
Even if there were 100 school shootings a year, our culture does not "behave this way," that's still a very OUTLIER statistic from the norm.
If you didn't impose anecdotes on everyone, i.e. fallacy of over-generalization, you'd be able to see the clearer picture.
School shootings up - overall homicide down = less violent, per capita, as a culture.