Cook the orzo according to the package directions. Drain, rinse briefly under cool water, and let it cool completely.
Add the olive oil, lime juice, minced garlic, salt, and black pepper to a small jar or bowl.
Shake or whisk until the dressing is well combined.
Add the cooled orzo, cooked shrimp, mango, avocado, arugula, cherry tomatoes, red onion, and cilantro to a large bowl.
Pour the lime dressing over the salad.
Toss gently until everything is evenly coated.
Taste and adjust with more lime juice, salt, or pepper if needed.
Serve immediately or chill briefly before serving.