We’re flawed because we want so much more. We’re ruined because we get these things and wish for what we had.
The Reclaimer(or the "recliner" as my spell check would have you believe) trilogy is more then likely about Humanity reclaiming their lost empire and the mantel left to them by the Precursors of which both were stolen by the Forerunners.
And as for the quotes above what the Gravemind is referring to is the Human flood war that took place some 115,000(?) years ago. Not John being a decedent of the Forerunners as the previous trilogy would have you believe.
And Spark had been rampant long before we ever got to him so why believe a word he says?
/Crptum and Primordium will explain allot more and allot better then me.
[Edited on 01.30.2012 3:24 PM PST]