They still get through and do damage. Salman Rushdie and Jair Bolsonaro come to mind on recent-ish high profile knife stabbings.

Obviously attacks happen even without guns. But it is harder to kill someone without a gun, and harder to kill multiple people or from a distance without one.

Guns aren't as generally useful as knives. So it makes little sense to have 1.2 guns per person, or really any private gun possession. The price of mass murders, shooter drills, and firearm accidents aren't worth what marginal benefits guns may bring.