An ethos and habit of being prepared (for all sorts of things and generally) will help a person get more from life and mitigate the risks that come with it. Like you say though, one cannot be prepared for everything but having the right attitude about it all means a person is probably much more equipped to handle things when they go pear shaped.
This is not the smallest caliber for a hunting rifle?
It depends what one is hunting. An air rifle (pellet gun) will kill an animal, but killing should be done humanely so the right calibre needs to be used. So, I'd not really use a .22LR for much other than rabbits I guess although it would kill a human with a well placed shot and the right range. A better all-round calibre might be .223 (556) although they're much louder which is why most preppers prefer to also have a .22LR. It can be a complicated discussion as it depends on where one is (available game) and other factors besides.
I saw that there is an even smaller .17 just right for killing rats in the field.
Yeah, the .17HMR. it's not my thing, I hit harder with my fist.
You say that because you are strong in your hands, as they say, you are in training 🙂