Cry about why the heck it had to be CABBAGES cause I HATE cabbages and then I'd probably just throw them at things for different foods, like uhhh...fruits and small animals. Cabbage weapons?
Oh goodness lol
First, assuming that this island is LITERALLY nothing but like a lump of sand surrounded by water and no trees/plants, I would spell out "HELP" in the sand with some of them. Afterwards, I would try to find the best place/way to preserve the remaining cabbages for food. As much as I hate greens, I will have to eat whatever I can to survive until help arrives. Next, after securing the cabbages, I would probably try to spend a little time carefully scrounging around the waters around me for any materials I can use for possible shelter from the sun, even if it's just to get it off my head/shoulders. My next step would be to try and get any plant life from the ocean and set it out in the sun to dry so I can use it for a fire. After setting aside the plants to dry, my next step would be to try and figure out a way to hunt for fish. I'm not a fan of fish, but again, I must survive. Along with this I will more than likely be looking for ways to boil water, or filter it in any way since it's not good to drink salt water, or any kind of unfiltered water. Any steps after this would be to further this little island base for better temporary living, as well as a possible way to, as safe as possible, tread the waters in search of help or better land...preferably civilized.
So ye lul