To prepare filling: Heat oil in a Dutch oven over medium heat. Add onion and bell pepper; cook, stirring often, until softened, about 3 minutes. Add garlic and cook, stirring, for 30 seconds. Stir in zucchini; cook, stirring often, for 3 minutes. Stir in chili powder, cumin, cinnamon and salt; cook for 20 seconds. Pour in tomatoes; bring to a simmer. Remove from the heat. Stir in shrimp and cilantro. Pour into a 9-by-13-inch baking dish.
Preheat oven to 350°F.
To prepare cornbread topping: Whisk flour, cornmeal, baking powder and salt in a large bowl. Whisk milk, oil, egg and honey in a medium bowl until smooth. Pour into the dry ingredients and stir just until moistened. Drop by heaping tablespoons over the shrimp mixture.e the casserole, uncovered, until the top is browned and the filling is bubbling, 40 to 45 minutes. Let stand for 10 minutes before serving (or follow make-ahead instructions).