Heat the oven to 350°F and grease a 2-quart baking dish (8-inch square pan or similar). Make the filling: In a large mixing bowl, combine the fruit, sugar, cornstarch, lemon juice, and ginger. Mix well and pour into the prepared baking dish. Make the topping: In a large mixing bowl, combine the flour, sugar, salt, and cinnamon and mix briefly to combine. Add the butter and work it into the dry ingredients by hand, using a rubbing motion, until the mixture resembles a crumbly cookie dough. If this mixture gets too warm, or the butter was very soft, it can end up clumping together to form a cohesive ball of dough. If this happens, be sure to crumble into small pieces before proceeding. Scatter the crumbles of dough evenly over the fruit and bake for about 45 minutes or until the topping is golden brown and the filling is bubbling all the way through. If the topping begins to get too brown before the filling is fully cooked, lightly tent it with foil to prevent it from getting too brown. Let cool for at least 30 minutes before serving, with ice cream if you like. The crumble topping can be made up to three days ahead and stored in the refrigerator.