I have
addressed (and refuted) the claim that Joseph Smith did not know that OT Elijah
and NT Elias were one and the same person, and that Joseph and many of his
contemporaries used “Elias” to denote a “forerunner”:
See also:
Further evidence that Joseph Smith used "Elias" in a generic manner to denote a forerunner can be seen in JST John 1:28, where Joseph expands upon the words of John the Baptist in his description of the Messiah:
He it is of whom I bear record. He is that
prophet, even Elias, who, coming after me, is preferred before me, whose shoe's
latchet I am not worthy to unloose, or whose place I am not able to fill; for
he shall baptize, not only with water, but with fire, and with the Holy Ghost. (Inspired Version [1867 RLDS Edition])
Here is page 106 of the JST Manuscript 2, Folio 1 for this verse (with "Elias" highlighted):
Needless to say, Joseph Smith did not believe that Jesus was OT Elijah; instead, this is further evidence of Joseph Smith used "Elias" to denote a forerunner.