Your premise is flawed.
Homicide rate in the UK (guns, knives, screwdrivers, whatever) is ~80% lower than in the US so I wouldn't describe it as "crazy".
If it was easier to kill it via other means why would all these mass shooters choose the harder way via guns? You're not making any sense. You bring up an arson example from last year and California wildfires... there is a mass shooting nearly every day.
https://www.usatoday.com/story/news/nation/2018/11/08/thousand-oaks-california-bar-shooting-307th-mass-shooting/1928574002/
See you are just using circular logic. I say it is not easier. I give examples.
You say "If it was easier to kill it via other means why would all these mass shooters choose the harder way via guns?"
This is circular logic, you are just referencing your own unbased conclusion as the source for your logic.
My point is even if you waved a magic wand to make all the guns go poof, those shootings would magically transform into arsons, stabbings, bombings, etc. Murders don't happen because of inanimate objects. They happen because of intent. Furthermore those inanimate objects help protect people from all of this, so it is not as simple as "oh lets just get rid of that and the problems will be gone!"
Now im intrigued to know how much deadly cases per 100k we have when we compare all western nations/industry nations.
Seems to me violence is quite the big problem in the usa.
Edit
https://www.statista.com/statistics/195331/number-of-murders-in-the-us-by-state/
Highest homicide rate with close to 75% attributed to guns.