In 1537, Pope Paul III declared in a Papal Bull that American Indians were human.
Notes on verification
Multiple independent, high-quality sources (Wikipedia, NIH Native Voices, EBSCO) confirm the 1537 papal bull Sublimis Deus declared indigenous Americans 'truly men' with rational souls and rights, condemning their enslavement. Minor nuance: exact wording is 'truly men' rather than 'human', and enforcement was later weakened.
Sources
- Books: Beyond Clovis - Archaeology Magazine Archive (archive.archaeology.org)
- https://www.nlm.nih.gov/nativevoices/timeline/185.html (nlm.nih.gov)
- https://www.ebsco.com/research-starters/history/pope-paul-iii-declares-rights-new-world-peoples (ebsco.com)