Who built the Sphinx, and when? And what was its original purpose or meaning

While conventionally attributed to Pharaoh Khafre (builder of the second pyramid at Giza) around 2500 BC, some geologists argue that the deep erosion patterns on its body suggest it was carved at a much earlier period, possibly by rainfall from a time before the Sahara became a desert (thousands of years earlier). The head, possibly recarved later, appears disproportionately small compared to the body