Drifter,

Are you bringing checked luggage or just carryon?
Certain items can only go in checked luggage.

As G&K mentioned, cash is KING!
Any canned goods can be picked up at HiLo.

Do you know any of your hotel staff? Do you have contact info for them?
I would suggest you contact any locals you know and ask them if they need anything.
Stay in you budget!!

When I was at LTU 2 weeks after the storm, I gave items to the staff and they helped spread them out to family and friends in the community.
Every Jamaican was either impacted by the storm or knows family or friends who are in need.

I would suggest the following items that aren't too bulky or heavy:
Feminine Hygiene products
baby wipes
Bug Spray Mosquito coils
Power packs that can recharge phones (I buy them on Amazon and they are inexpensive and small).

Enjoy,

VVHT aka Happy