The perfect beast is humanity's self-made doom.
The beast that we keep building is a (modern/future) human, that has lifted itself "All the way to Malibu out of the land of talking drum"; someone who has "The power of reason" and is "the top of the heap", someone who "kills things he doesn't eat".
The whole song is a description of a self-created doom based on our self-destruction:
We've found the lock and turned the key
We're shakin' up those building blocks
Going deeper into that box- (Pandora wouldn't like it)
We have the power to get our life better and longer, we are trying to become gods (
"Olympus or bust!") yet there is a price to pay.
Relieve all pain and suffering
And lift us out of the dark
Turn us all into methuselah-
But where are we gonna park?
The semi-religious "Glory hallelujah!" is used sarcastically here - we are creating our own doom and we are happy to do so, because
For we have met the enemy -and he is us