I was in middle school when Columbine happened.
At the time, it felt like a national watershed. In hindsight, I actually don't know the degree to which Columbine stood out from other school shootings, versus whether it just happened to be "the" big shooting that occurred in the formative part of my life where I began paying attention to such things. Maybe for people born a few years earlier or a few years later, a different school shooting was "the" shooting. Lord knows we don't lack for choices.
Nonetheless, I remember thinking then that obviously Columbine was going to prompt us to do something about gun violence. There was no chance that our collective response to that tragedy would be to do nothing. As a kid, you believe adults are interested in protecting you. Perhaps as an adult, without strong evidence to the contrary, you also believe other adults will take the steps necessary to ensure children aren't being gunned down in schools or in streets.
But, more than 20 years later, our response to school shootings has indeed been: essentially nothing. We can't say we're still "working on it", or that we're still processing. At this point, it is fair to say America has made a conscious choice as a polity that we find school shootings to be an acceptable price to pay in exchange for allowing guns everywhere.
Twenty years after Columbine, nobody can pretend as if we don't know the consequences of our choices. We chose to let Oxford happen. We'll no doubt choose to let the next one happen too. There is nothing surprising or shocking or even unexpected happening anymore. Each of these deaths is attributable not just to the loathsome gunmen who pull the triggers, but to choices we've made collectively as a community. We are committed to an open highway of free, unfettered access to guns, and these bodies are the change the NRA throws into the tollbooth on the way.