I’ve replaced “horizontal” with “Mouse X” and it works just fine. There seems to be no movement when i press the left/ right keys.
float move = Input.GetAxis("Horizontal");
Vector2 new_pos;
new_pos = new Vector2(C_Rigidbody2D.position.x + (move * 2), -9);
C_Rigidbody2D.MovePosition(new_pos);
}