Yank here, but some feedback-
Years ago my dad got an offer to work on a cruise ship. He was working as a Registered Nurse for some time, and a cruise line wanted to recruit him to work on the ship’s infirmary. He considered it because of the opportunity for travel, but eventually opted out.
My guess is that if you have some specific skill (medical license, engineering/electrical/etc skills) you might have a better chance of working on a ship like that without being a total ‘worker bee’.
Not to sound racist here, but on the cruises I’ve been on (Princess and Carnival) most of the busboys/maintenance/kitchen personell were Filipino. The British fellas there were the ones driving the ship, or filling some other critical/management function. It made me wonder if those more mundane jobs were only attractive to people who come from countries where the pay for a cruise ship busboy is relatively lucrative to what they might make in their home country.