Wherefore, I write a few more things, contrary to that which I had supposed; for I had supposed not to have written any more; but I write a few more things, that perhaps they may be of worth unto my brethren, the Lamanites, in some future day, according to the will of the Lord.
Moroni is writing this for the Lamanites. Past LDS leaders and various references in the Doctrine and Covenants make it clear that the Lamanites were the Native Americans (as well as Pacific Islanders according to the leaders). Now, LDS leaders won’t tell us who the Lamanites are. Just who is it that Moroni is writing to?
Paleontology, archaeology, philology, and population genetics indicate there were no descendants of Israel in the pre-Columbian Americas.