They don’t act on their own though, they’re a chain reaction that a human must start.

At some point, you need to start blaming the tool, not the user of the tool. Imagine I hire you as my personal assistant. One day I give you a shopping list and tell you to go get those things for the lowest cost you can manage. You then go and break into someone's house, steal a gun from there, go to a grocery store, load up your cart, and shoot any staff there who try and stop you. You then come back to me, load of groceries in hand, and proudly announce you got it all for zero dollars. I had zero desire or intention for you to do that. In this scenario, you just happen to be a complete sociopath who took my instructions in a direction I never would have intended. In this case, I'm innocent (as long as I was unaware of your personality.) The moral responsibility is on you.

Sure, humans must provide the initial push for these systems, but they're chaotic and unpredictable. They can act in ways that cannot be anticipated by the humans instructing them. At that point, the moral agency really isn't on the human instructing them anymore. The moral agency is on whatever company built this dangerous AI tool and allowed people to use it. The tool itself is the problem, not just the person wielding it.