I suppose Blue Cheer usually gets the nod for having the first Heavy Metal song for "Summertime Blues", but I think that's more psychedelia.  "Helter Skelter", 1968, power chords that crack your rib cage, and Paul's raw voice, straight ahead take no prisoners heavy rock n' roll gets my vote even though Heavy Metal as we know it didn't exist back then, this has got to be mold.

This topic has come up before in other places and I think the basic concensus was that the first heavy metal song was Duane Eddy/Rumble, or a few of the early Yardbirds songs.

I suppose it just depends how far back you want to go and how you would define heavy metal.

I always felt the the first real 'heavy metal' song was 'All Day And All Of The Night' by the Kinks. Probably wrong though.

No, the Kinks songs came up as well.

It really depends on how one thinks of heavy metal.  Som e swear before Zeppelin there was none.  Other refer to Cream, or further back the Yardbirds.  But the Kinks, specifically those two songs (one you mentioned and You Really Got Me) are often cited as being even before anyone else.

I don't buy the Duane Eddy view, and I would have to say you are probably correct on the acknowledged first.