If Joseph Smith wrote the Book of Moses, wouldn’t we expect him to emphasize the greatness of God rather than the “nothingness” of man? Moses 1: 9-10 reads:
And the presence of God withdrew from Moses, that his glory was not upon Moses; and Moses was left unto himself. And as he was left unto himself, he fell unto the earth.
And it came to pass that it was for the space of many hours before Moses did again receive his natural strength like unto man; and he said unto himself: Now, for this cause I know that man is nothing, which thing I never had supposed.
This figure of speech known as litotes deemphasizes one thing in order to emphasize another. While we may expect to see this in the Bible, wouldn’t this be unnatural to Joseph Smith?