Yes, guns destroy human beings, that is their purpose. And it is difficult for a lot of people to grapple with the idea that such seemingly fundamentally, some would say, evil devices can be used for good.
The comparison with cars is a good one though. Cars are an example of how lethal power exists in the hands of many in society. And that's true to an enormous degree, not just with cars though they are a prime example. Most people have the ability to take the lives of others without a great deal of effort. Imagine what would happen if, say, 1ppm of humanity woke up and decided to do murder that day. There would be a lot of killings. And yet society is still largely peaceful. Because most people can be trusted with the lives of their fellow humans. And it's important to realize how deeply we take that for granted. Something as simple as riding a bus or driving in traffic represents a tremendous trust in our fellow citizens to not murder us, and they trust us not to murder them as well.
Firearms do not represent injecting a unique capability for death and injury into society, they're just make that aspect of daily life more blatantly obvious. But just as with cars, knives, fists, pencils, hammers, bricks, fire, and all that most people can be trusted with firearms most of the time. And indeed when firearms are allowed into the hands of citizens of good intent they can be used to thwart crimes quite often. Many rapes and roberies have been stopped by firearms, often just by the mere presence of a firearm (not even counting the deterrent effects). And in some spectacular cases firearms have been used defensively to stop mass murders in their tracks. But these examples tend to be less dramatic than successful mass shootings, so they tend to be less well known.
On the whole, the point still stands, it is safer for the average person to own a gun than to own a car. And that is a testament to the trustworthiness of the average citizen, and the degree to which many people take gun ownership seriously and solemnly.