Church manual from 1910 teaches that Adam was probably not the first man ever created, but the first man for this earth; man is also "in the most literal sense, a child of God."
Course of Study for the Quorums of the Priesthood Church of Jesus Christ of Latter-day Saints Priests Second Year Divine Mission of the Savior (Salt Lake City: The Church of Jesus Christ of Latter-day Saints, 1910), 35, M251.43 P949 1910, Church History Library
LESSON FOURTEEN.
SUBJECT: The Creation of Man
1. Man has descended from God; in fact, he is of the same races as the Gods. His descent has not been from a lower form of life, but from the Highest Form of Life; in other words, man is, in the most literal sense, a child of God. This is not only true of the spirit of man, but of his body also. There never was a time, probably, in all the eternities of the past, when there was not men or children of God. This world is only one of many worlds which have been created by the Father through His Only Begotten. Adam, then, was probably not the first mortal man in the universe, but he was likely the first for this earth.