What were Giza and the Nile Delta like in 6000-3200 B.C.?
Well, one reason is that it is highly likely that if the face was carved in 6000 B.C. and the head, front chest and limbs by 5600 B.C., it is very probable that all original knowledge about the creation of the Sphinx's face would have been lost by 3000 B.C..
I believe there was, however, a very old preliterate connection (c.6000 B.C. and perhaps even earlier) between the predecessor of the Sphinx (my suggested "Veiled face" at Giza) and the location of what was to eventually become Heliopolis. The first indication of that older connection took the form of a Sphinx/Ra cult emerging c. 2686 B.C. that continued to flourish under different names until around 1070 B.C.