Elder Jeffrey R. Holland discussed six possible explanations for Jesus’s statement that He had never shown Himself to man prior to showing Himself to the brother of Jared:
“One possibility is that this is simply a comment made in the context of one dispensation and as such applies only to the people of Jared and Jaredite prophets—that Jehovah had never before revealed himself to one of their seers and revelators. …
“Another suggestion is that the reference to ‘man’ is the key to this passage, suggesting that the Lord had never revealed himself to the unsanctified, to the nonbeliever, to temporal, earthy, natural man. The implication is that only those who have put off the natural man [and are] sanctified (such as Adam, Enoch, and now the brother of Jared)—are entitled to this privilege [see D&C 67:10–11].
“Some believe that the Lord meant he had never before revealed himself to man in that degree or to that extent. This theory suggests that divine appearances to earlier prophets had not been with the same ‘fulness,’ that never before had the veil been lifted to give such a complete revelation of Christ’s nature and being.
“A further possibility is that this is the first time Jehovah had appeared and identified himself as Jesus Christ, the Son of God, with the interpretation of the passage being ‘never have I showed myself [as Jesus Christ] unto man whom I have created.’ That possibility is reinforced by one way of reading Moroni’s later editorial comment: ‘Having this perfect knowledge of God, he could not be kept from within the veil; therefore he saw Jesus.’
“Yet another interpretation of this passage is that the faith of the brother of Jared was so great he saw not only the spirit finger and body of the premortal Jesus (which presumably many other prophets had also seen) but also some distinctly more revealing aspect of Christ’s body of flesh, blood, and bone. …
“A final explanation—and in terms of the brother of Jared’s faith the most persuasive one—is that Christ was saying to the brother of Jared, ‘Never have I showed myself unto man in this manner, without my volition, driven solely by the faith of the beholder.’ As a rule, prophets are invited into the presence of the Lord, are bidden to enter his presence by him and only with his sanction. The brother of Jared, on the other hand, seems to have thrust himself through the veil, not as an unwelcome guest but perhaps technically as an uninvited one. Said Jehovah, ‘Never has man come before me with such exceeding faith as thou hast; for were it not so ye could not have seen my finger. … Never has man believed in me as thou hast.’ Obviously the Lord himself was linking unprecedented faith with this unprecedented vision. If the vision itself was not unique, then it had to be the faith and how the vision was obtained that was so unparalleled. The only way that faith could be so remarkable was its ability to take the prophet, uninvited, where others had been able to go only with God’s bidding” (Christ and the New Covenant, 21–23).