Of course, the true Amon god didn't actually exist; he was merely the personification of the world's failed creation, nothing more—at least, until today.
As for after... Ra looked at the power that legally belonged to "Amon," which the world had proactively bestowed upon himself, and he finally made up his mind.
Even the gods of Hemenu can die, and even grow old and pass away, including himself. As the supreme deity, Ra had been contemplating ways to solve this problem for a long time.
Luckily, after a lengthy exploration, he did indeed find a way to change this outcome because Hemenu's [Sun] held powers not possessed by Chaos; it inherently possessed the capabilities of [rebirth] and [renewal].
He planned to be reborn in some way just as he was about to age, then, just like he had devoured Atum, allow the new self to consume the old self in order to avoid decay and death.
