Might be cutting it close on the time. When you get onboard the Ship, take your plane tickets to the front desk to show them you have an early flight, and they will put you in the first group to disembark the Ship. I would take a cab from the Cruise Terminal to the Airport, and not waste time on a shuttle. If the Ship arrives on time (weather permitting), and Customs and Immigration goes smoothly, the boat will probably start letting people off at 7:00 or so. You should be to the airport 1 to 2 hours early, and you might beat the crowd from the other Cruise Ships and make your flight. I would not feel comfortable with the time you have, but if everything is already set in stone so that no changes can be made, enjoy your Cruise, and hope the Airport has things running smoothly.
Good luck !!