If using bamboo skewers, soak them in water for at least 20 minutes. Preheat the broiler or prepare the grill.
In a large bowl, whisk together the jerk sauce, (or jerk seasoning, if using) 1/2 cup olive oil, and ginger. Add the shrimp and toss to coat. Cover and marinate for 15 minutes.
In a separate bowl, toss the tomatoes, onions, peppers, and parsley with the remaining 2 tablespoons olive oil. Season with salt and pepper. Skewer the vegetables and shrimp.
Place the skewers on a rimmed baking sheet lined with aluminum foil, or, if grilling, place on the grill. Cook, turning once, until the vegetables are tender and the shrimp are opaque, 5 to 6 minutes more. Garnish with parsley before serving.
Combine all ingredients but vegetable oil in a bowl until well-mixed. Add oil to create a marinade to your desired consistency. Store in an airtight container.