It has been several decades since I read his book,”Carrying the Fire”, but I thought I remember his writing that he would have been mission commander on Apollo 5, had the Apollo 1 fire never happened.
That’s one book I have not read, so your information may be more correct than mine. It obviously goes back aways because it is using the “old” numbering system for the manned missions, Apollo 1, 2, etc. After the fire, the unmanned missions filled in the numbering gap between Apollo 1 (the one that burned) and Apollo 7, the eventual first manned mission.