Did Jimi discover progressive rock by accident?

I recently downloaded the Studio Sessions Volume 1 compilation and noticed a very interesting recording in this compilation, Js31 Jam Messenger (take 15). I was thinking the song was incredible until I suddenly realized that there was a piano in this Jam. I was paying attention to the drums, guitar and piano simultaneously and this song simply reminds me a lot of progressive rock. However, this Jam recording is from October 1968. And the first progressive rock bands began to appear in the early 70s. I wanted to understand if this music really is progressive rock and if Jimi was really the first to discover this style.