ultmetal: I don't really think anyone would deny bands like Black Sabbath and Judas Priest were metal, really.
But as far as some of the bands go, I definitely don't believe Aerosmith or Led Zeppelin ever said they were a metal band. If there is an interview that indicates where they said so, when was it?
Sabbath were the first metal band.
Acts such as Led Zeppelin, Jimi Hendrix, etc. were not really metal bands, but did pave the way for what would eventually become heavy metal.