I will not address his other hypotheses, which I do not find persuasive, that the Sphinx was the jackal [wild dog] Anubis (Anubis, associated with the dead and the afterlife, would look to the west, not face east as the Sphinx does) and the face seen on the Sphinx is that of the Middle Kingdom pharaoh Amenemhet II, though I note the original Sphinx has been reworked and the head re-carved.
For a review of the evidence bearing on the age and significance of the Great Sphinx, see my book with Robert Bauval, Origins of the Sphinx.
Back in the early 1990s, when I first suggested that the Great Sphinx was much older than generally believed at the time, I was challenged by Egyptologists who asked, "Where is the evidence of that earlier civilization? They were sure that sophisticated culture, what we call civilization, did not exist prior to about 3000 or 4000 BCE.
In fact, the Sphinx may not have originally been a sphinx at all.
Perhaps it was a lion – actually the latest evidence suggests it was originally a lioness. The southern wall of the Sphinx Enclosure showing water (via rainfall) erosion.
This is due to ancient rains and the paleohydrology of the area.
This erosion is not compatible with pooled water in the enclosure.
The Great Sphinx of Egypt in its enclosure, with a diagram indicating the deep fissures and undulating surfaces created by water (rainfall) weathering and erosion.