> But the notation does leave something up to the performer, just a bit more than usual.
We don't know how much the notation leaves up to the performer. For all we know there could have been a formal system for tuning the instrument this was intended to be played on and a formal system for rhythm; a musical tradition that makes it very obvious how the piece should have been performed that is now forgotten.
> Relative changes are what makes the melody, you could transpose it up or down and stretch the pitches every way that you want, change the tempo etc but it still would be (for me, at least) recognizably the same melody.
This is not simply a matter of transposition or a tempo difference. No one knows the relative changes in pitch.
We don't know how much the notation leaves up to the performer. For all we know there could have been a formal system for tuning the instrument this was intended to be played on and a formal system for rhythm; a musical tradition that makes it very obvious how the piece should have been performed that is now forgotten.
> Relative changes are what makes the melody, you could transpose it up or down and stretch the pitches every way that you want, change the tempo etc but it still would be (for me, at least) recognizably the same melody.
This is not simply a matter of transposition or a tempo difference. No one knows the relative changes in pitch.