we book the air/cruise through carnival all the time, we have allways got at the airport at about 1;30 and everything is ok for us. it costs a little more and we have the ins. for us its just peace of mind knowing they are there waiting.
Jerome, your travel insurance, whether purchased with the cruiseline or not will be of no value to your for a flight delay or cancellation if you don't follow the flight guidelines of the cruiseline. Read the policy, you have a policy that is useless for a 1:30 flight.
For a 4:00pm ship departure you need to set inbound flights, in most cases (ships and cruiselines vary slightly) to be on the ground no later than 12:00 noon. You normally need even more time for outbound flights because of disembarkation timeframes.
F, change your flight. You could possibly make it but it's not worth the risk. You risk not only money if you miss the ship, you risk loosing your vacation. I can live without the money but losing my vacation and the money would make me really hard to be around for a while.