Preheat oven to 425F (220C). Line a baking sheet with foil. Slice zucchini into rounds about 1 inch (2.5 cm) thick. Place in a very large bowl. Peel potato only if you wish. Slice into wedges about 1 inch (2.5 cm) thick. Core and seed peppers, then slice into thick strips. Cut onion into quarters. Add potato, peppers and onion to bowl.
Add chicken to bowl. Drizzle with oil and sprinkle with paprika, cinnamon, cayenne, salt and pepper. Toss until evenly coated. Tumble onto baking sheet. Spread chicken and veggies evenly in one layer. Roast, uncovered, in centre of 425F (220C) oven 30 minutes. Turn chicken and stir vegetables. Continue roasting until chicken feels springy when pressed and veggies are tender, 15 to 20 more minutes.