Webster’s 1828 English Dictionary notes that the term Indian is “is particularly applied to any native of the American continent.” That is, it need not apply exclusively to the native peoples of the United States, but to all those found throughout the Americas.
Evidence of this usage is abundant. He is a random passage from John L. Stephens 1841 work, Incidents of Travel in Central America.
The prefeto was well versed in the history of Palenque. it is in the province of Tzendales, and for a century after the conquest of Chiapas it remained in possession of the Indians. Two centuries ago, Lorenzo Mugil, an emissary from Rome, set up among them the cross. The Indians still preserve his dress as a sacred relic, but they are jealous of showing it to strangers, and I could not obtain a sight of it. The bell of the church, too, was sent from the holy city. The Indians submitted to the dominion of the Spaniards until the year 1700, when the whole province revolted, and in Chillon, Tumbala, and Palenque they apostatized from Christianity, murdered the priests, profaned the churches, paid impious adoration to an Indian female, massacred the white men, and took the women for their wives. But, as soon as the intelligence reached Guatemala, a strong force was sent against them, the revolted towns were reduced and recovered to the Catholic faith, and tranquility was restored. The right of the Indians, however, to their ownership of the soil was still recognised, and down to the time of the Mexican Independence they received rent for land in the villages and the milpas in the neighborhood.
Stephens, Incidents of Travel in Central America, 1841, 2:386, emphasis added.
In 1845 the Quorum of the Twelve Apostles, issued an official proclamation which stated
We also bear testimony that the Indians (so called) of North and South America are a remnant of the tribes of Israel; as is now made manifest by the discovery and revelation of their ancient oracles and records. And that they are about to be gathered, civilized, and made one nation in this glorious land They will also come to the knowledge of their forefathers, and of the fullness of the gospel; and they will embrace it, and become a righteous branch of the house of Israel.
Proclamation of the Twelve Apostles of the Church of Jesus Christ of Latter-day Saints. To All the Kings of the World; To the President of the United States of America; To the Governors of the Several States; And to the Rulers and People of All Nations (New York: 6 April 1845), emphasis added.