It is required to have a valid Passport to enter Jamaica. Additionally, your Passport expiration date has to be six months beyond the end of your trip. For example, this year the Feast ends on October 10. Therefore your Passport should not have an expiration date earlier than April 11, 2021.
However, due to Covid-19, the US has stopped issuing Passports unless it's a 'life-or-death' family emergency. You can read the Policy here: https://travel.state.gov/content/travel/en/passports.html/
I will be checking the website often for an update and I will let you know when you can apply for a Passport if you need one.