The original manuscript is no longer extant here. Oliver Cowdery, while copying from 𝓞 into 𝓟, first wrote “who created all things”, probably because of the high expectation of all things after the verb create. In the King James text, there are four occurrences of “create all things”: Ephesians 3:9, Colossians 1:16 (two times), and Revelation 4:11. In the Book of Mormon, there are 12 occurrences of this phraseology, including three at the beginning of 2 Nephi:
Here in Jacob 2:21, the immediately preceding occurrence of “such things” probably helped Oliver to initially write things rather than flesh.
No other passage in the Book of Mormon text refers to “creating flesh”; in fact, such phraseology is not found in the biblical text. Thus there would have been no motivation here for Oliver Cowdery to have edited things to flesh. The original manuscript undoubtedly read flesh. Moreover, the correction in the printer’s manuscript is inline and is without any change in the level of ink flow.
Summary: Maintain the corrected reading of the printer’s manuscript (“who created all flesh”), which was undoubtedly the reading of the original manuscript.