Moreover, we have records from some of these precolonial intellectual traditions in the Americas. The nahua genre of huehuetlatolli is an excellent example in many ways. The selectively preserved bits we have resemble something closer to Confucianism than mathematics, but keep in mind we have a narrow selection from a single genre in a much wider landscape.
In what's now US territory, proto-writing systems (emoji are a modern example of these) existed. There were also intellectual traditions associated with them, particularly among southwestern groups like the Puebloans. Those are relatively closed to academics for a variety of historical reasons and consequently understudied, but we know they existed.