Well, hammers, knives, cars, swimming pools, and baseball bats main use is for something other than killing people. And even though guns really only use is to kill and/or maim, I still see how they are useful for the purposes that I mentioned.
Regarding your comment about the largest mass shootings, you are incorrect stating the largest mass shooting was the pistol at VT. That was 32 deaths. The actual largest was the 60 killed in Las Vegas followed by the 49 killed in Orlando at the Pulse nightclub.
In 10 minutes, the Las Vegas shooter was able to get off over 1,000 rounds killing 60 and wounding over 400. The Orlando shooter was able to get off 200 rounds in less than 5 minutes.
As you said, the VT event was horrible with multiple deaths. However, they occurred over a few hours' time. Imagine, if his weapon of choice was an AR15? Of course, it would be ideal to eliminate those events from occurring as well, but I don't think all guns should be outlawed.