While critical of the Book of Mormon, Protestant John Wayne Wardell notes that the 1830 Book of Mormon listing Joseph Smith as its "author" and "proprietor" does not mean that, originally, Smith claimed to have been its author (read: it was fiction, etc):
Smith lists himself as the
“author and proprietor” in the first edition of the Book of Mormon in 1830.
Some critics have suggested that this is evidence that Smith admits he was the
author, and not God. However, this was clarified in the preface of the 1830
edition where Smith specifies that he just translated the record. Mormons
defend their founder here by noting that copy-right laws require a human author
be designated to get any work published. So, Prophet Smith just attached his
name as the author for publishing purposes. This Mormon argument is reasonable
enough, for Smith always proclaimed through his entire life that God Himself
was the Divine author of the Book of Mormon. (John Wayne Wardell, The
Footprints of Mormonism [London: Austin Macauley Publishers, 2025], 153)
The 1830 Book of Mormon listing Joseph Smith as “Author and Proprietor”
John Whitmer and Joseph Smith being the "author and proprietor of the Book of Mormon"
John H. Gilbert on Joseph Smith being the "Author and Proprietor" in the 1830 Book of Mormon