I know before Puerto Rico became the prize for competing imperial nations there was a thriving culture. Unfortunately I’ve found painfully little about the religious practices and folklore of the Taíno or Arawakan people.
Were they polytheistic? What were their gods like? Any notable heroes (I’ve heard of Guama)?
This is a big question. I’d appreciate even general guidance about where I can find answers.
While I don't know much about Taíno mythology myself, if you can find the book Caciques and Cemi Idols by Jose Oliver, you'll be in good shape. Oliver goes in depth into the mythology of the cemi idols, their histories, and the Taíno in general. I wish I could provide more help and actually provide an answer but this is a good start!