Upvote:1
From https://www.pica.gov.jm/immigration/travel-documents-required Jamaicans travelling on a Jamaican passport have an automatic right of entry into the island and do not require a visa to enter. Jamaican citizens are required to present the following documents to Immigration:
A valid Jamaican passport, an emergency certificate or an expired Jamaican passport (providing acceptance from the airline)
A completed and signed Immigration/Customs C5 form, either online or a physical form
So yes, you can buy a one way ticket but you should check the airline will allow you to board on that basis before doing so.
Also note the comment from @Willeke regarding the possible cost of one way tickets.
Answer assumes you have a valid US passport.