Melt butter in a large skillet over medium-high. Add corn and onion; cook, stirring occasionally, until tender, 8 minutes. Stir in cream cheese, half-and-half, pepper, and 1 teaspoon of the salt. Cook, stirring constantly, until cream cheese melts, 2 minutes. Stir in chives. Remove pan from heat; cover to keep warm.
Heat oil in a separate large skillet over medium-high. Add sausage; cook, stirring occasionally, until browned, 6 minutes. Drain on paper towels, reserving drippings in pan. Sprinkle shrimp with remaining ¾ teaspoon salt. Add to pan; cook over medium-high, stirring occasionally, until shrimp turn pink, 3 minutes.
Serve corn topped with sausage, shrimp, chives, and parsley.
