No worries, cozumel is a straight up tourist town.. probably over 95% .. you'll be fine... Pick a good excursion,, I wanted atv ride, or jeep ride,, or horseback ride,, wife wanted shopping tour.. guess what we did lol.. we did get a tour of the whole island,,, highlight was a tequilla factory tour with tasting..
Judging by your post, you're going to be bored out of your mind.. the ship is only so big,, you will know every inch of it the first 4 hours.. my cruise was from Mobile years ago... 2 days on the water, 6 hours on Cozumel, then 2 more days on the water..