If Khufu is the result of gigantic construction - and I'm not certain as to the exact physical stature of the builders - then the interior of the pyramid was never meant for any entry by these same builders.
How could a giant fit down the Descending Passage?
So, it couldn't have been a tomb. Or a place of initiation. Or anything requiring human (at their time) interaction.
Unless dwarves (Bes) were involved.