In that last hypothetical we have no innocent accident, and we have no mere civil negligence—instead, we have, with the pointing of the weapon at the victims and the deliberate press of the trigger, criminal recklessness.
The gun did not go off for unforeseeable reasons, such as a hidden defect. The gun discharged because it operated as designed—to fire when the trigger is depressed. Of course, the gun must be loaded when the trigger is depressed in order to cause harm—but as the tragic consequences here amply demonstrate, the gun was loaded. It would be the duty of the person wielding the gun to ensure it was unloaded if they wished to cause no harm when they depressed the trigger—and clearly that duty was not met.
Second, anyone handling an inherently dangerous object such as a firearm would be presumed to possess the safety knowledge needed to handle that firearm safely around others—a claim of ignorance is no defense when one is handling inherently dangerous objects.
That guns are inherently dangerous is common knowledge presumed to be known to everyone. That the rounds fired come out of the muzzle and travel with lethal force and distance is also common knowledge presumed to be known to everyone. That guns discharge when their triggers are depressed is also common knowledge presumed to be known to everyone.
Because the various common knowledge just described would be presumed to be known to everyone, including Alec Baldwin handling the firearm, when he pointed the weapon at Ms. Hutchins and pressed the trigger (again, speaking solely within the context of our hypothetical, not as a claim of what actually happened), then he was necessarily aware of the risk of death he was creating, and deliberately disregarding that risk, with the result being the death of Ms. Hutchins. (The same would apply, of course, to Alec Baldwin’s violation of the gun handling safety rule of presuming at all times that a gun is loaded.)
When you are aware you are creating a risk of death, deliberate disregard that risk, and death results—that’s the very definition of criminal recklessness—commonly referred to as involuntary manslaughter.