All Rugers, and for that matter all currently manufactured pistols that I am aware of, have a firing pin block. If you remove the slide you can see how it works by depressing the firing pin block and the pushing in on the firing pin. Then let go of the block and you can't push the firing pin all the way because it is now blocked. As for the decocker, same thing, just observe how it is reacting when you depress the lever.
What this means is simple, the gun won't discharge if dropped or decocked, the trigger must be pulled.
What this means is simple, the gun won't discharge if dropped or decocked, the trigger must be pulled.