I reckon that legends of the primes' existence on earth, manifested through time and history and eventually became the basis for what early mankind referred to as their Egyptian gods:

Ra Prime (God the Sun)
Nuit Prime (God of the Sky)
Geb Prime (God of the Earth)
Amun Prime (God of Creation)
Thoth Prime (God of Wisdom)
Ma'at Prime (God of Justice)
Sekhmet Prime (God of Destruction, aka Fallen)

There was actually 13 original primes (created by Primus) but by the time they arrived on earth to harvest the sun's energy, only 7 remained...