Waaaaaaay back in the day, salt and sugar were used to extend the shelf life of many foods. That's all changed with the opportunities home-canning presents to us. We no longer have to worry about how much salt to use to cure meat in order to preserve it. (Even though it sure is yummy; bacon....) We don't have to use as much sugar in syrups to preserve fruit inside a jar. We can make jams and jellies with less sugar added pectin so more of the fruit flavor comes through instead of just tasting sweet.
Some folks still have in their head that home-canned food must contain extra salt and sugar in order to preserve the food. On the contrary, you can preserve most of your food without it. It is there solely for flavoring now. What a boon to folks with dietary issues that require less of either or both! This also allows us to cut down on how much we consume anyway. Commercially processed foods don't allow us to take any salt or sugar out of the product prior to consuming it.
I'm notorious for forgetting to add salt or not adding enough when I'm canning. I don't use a whole lot of salt when I cook. When I use my home canned ingredients, I feel like I need to add more to taste because the salt is already missing from the initial product.
I'm personally a fan of old-fashioned jam with the full hit of the sugar rush to keep you going. Most all my jams are made with regular pectin. Low and no sugar added pectin is available and you can experiment away with flavor combinations. In applesauce and fruit butters, I don't use as much sugar anymore. I want to taste the fruit. I use lighter syrups when canning fruit such as berries and pineapple. I don't like the blah flavor of those types of items without any sugar added. Making a light syrup is enough to support the fruit flavor without the candy-type mouth feel.
Because of this freedom; feel free to experiment with how much salt is included in a recipe. Sugar can be a fussy item in recipes containing pectin, so you have to watch that. Try some jams with low or no sugar added pectin. Experiment with a lighter syrup on fruit or by using honey in apple butter. Home canned food can be amazingly healthy and doesn't need to carry the old-fashioned connotation of being bad for you.