In a medium-sized bowl, whisk together the olive oil, freshly squeezed lemon juice, minced garlic, paprika, cumin, cinnamon, salt, and black pepper. Add the chicken pieces, ensuring they are thoroughly coated with the marinade. Cover and refrigerate for a minimum of 30 minutes, allowing the flavors to develop fully, or keep marinated for up to 8 hours for deeper infusion. Preheat the grill to medium-high and lightly brush the grates with vegetable oil to prevent sticking. Once ready to cook, thread the marinated chicken onto skewers, alternating with pieces of onion and bell pepper. Drizzle any remaining marinade over the assembled skewers. Arrange 6 to 9 skewers on the preheated grill and cook for approximately 10 to 15 minutes, rotating every few minutes to guarantee even charring and doneness. Once the chicken is thoroughly cooked and beautifully golden, remove from the grill and garnish with freshly chopped parsley. Serve warm with Lebanese rice or a side of your choice.