If using frozen cooked shrimp, thaw it safely in the refrigerator and pat it dry. Remove any remaining shells or tails, then chop the shrimp into small pieces. Reserve a few whole shrimp for garnish if desired.
Place the softened cream cheese in a medium mixing bowl. Beat with a hand mixer or sturdy spoon until smooth. Add the sour cream and mayonnaise, then mix until the ingredients form a creamy, uniform mixture without large lumps.
Stir in the lemon juice, Worcestershire sauce, minced garlic, paprika, black pepper, and a small amount of salt. Add cayenne pepper if you prefer a little heat. Taste the mixture and adjust the seasonings as needed.
Add the chopped shrimp, green onions, and fresh parsley to the creamy mixture. Fold gently with a spatula until the shrimp and herbs are evenly distributed. Avoid overmixing so the shrimp retains some texture.
Transfer the dip to a serving bowl, cover, and refrigerate for at least 30 minutes to allow the flavors to develop. Garnish with parsley, a light sprinkle of paprika, or reserved shrimp. Serve cold with crackers, toasted bread, or fresh vegetables.