Nope! If you booked the cruise lines air/sea package you are covered due to delays & cancellations. Remember you pay A LOT more for the cruise lines to take care of it for you. If you book your own air you are on your own.
If you took the cruiseline insurance but made your own air arrangements then no you are not covered . If you book your own air and take third party insurance and include the total cost of your trip then you would be covered.
You may still be able to cancel your cruiseline insurance and get other insurance instead. You could at least look into that.