Final answer:
Indigenous religions were the main religious beliefs in the Americas in 500-600 CE, with diverse practices among different tribes and civilizations. The arrival of European colonizers introduced Roman Catholicism.
Step-by-step explanation:
In the Americas in 500-600 CE, the dominant religion was indigenous or native religious beliefs. The native populations of the Americas had their own diverse religious practices, including nature worship, ancestor worship, and polytheism. These belief systems varied greatly among different tribes and civilizations, such as the Mayans, Aztecs, and Incas. The arrival of European colonizers, especially the Spanish, brought Roman Catholicism to the Americas and led to the conversion of many native populations.