Plus in Halo 3 on Installation 04 B 343 Guilty Spark call's him Forerunner, and on in an infected High Charity Gravemind calls MC "child of my enemy" enemy=Forerunners
No, and the logic used in this question is pretty hilarious. That's like asking "isn't my dog technically a person since dogs are descended from domesticated animals bred thousands of years ago?" Humanity is pretty much the closest thing to an inheritor of the Forerunners' Mantle (a religious concept held sacred by the Forerunners) and was in general held in higher regard than other races in existence around the time of the Forerunners, such as the Prophets. That is why they are reclaimers. Forerunners =/= Humanity. Read Cryptum.
As the guy before me said, read Cryptum. Humans and Forerunners are related in the same way you are to a koala. Yeah, really really far back we had a common ancestor, but the Forerunners were a more advanced species with capabilities such as spontaneous mutation for adaptive purposes. Pretty sure John's never done that.