Do I have to can to make jam?

Not at all. Especially if your fruit haul happens to be just a few handfulls of wild berries, it might not even be worth you time. Just scale down whatever jam recipe suits your fancy and pour it into a jar without a canning lid. Cooled, it’ll keep in the fridge for weeks.

The ubiquity of big basement freezers has also made so-called “freezer preserves” a very big thing. The only trouble there is that you’re forced to use plastic containers (either tupperware-type or freezer bags), and some people feel they impart a synthetic taste to their fruit. I’ve never noticed a big difference, provided the jam goes into the container fairly cool.