For those who want to read the classic version of the origin of Galactus, check it out in Thor beginning in #163 or see if you can find the condensed version in one one shot called Super-villain Classics #1 (1983) They are available on Marvel Unlimited
The issues credit Stan Lee & Jack Kirby but I don't think anyone would be surprised if 90% of this saga is Jack Kirby. The only thing is Vince Colletta is the inker. I think it looks like the Kirby work is there but he was known to erase stuff or just not ink it in.
the demise of Taa and the universe that existed at the time....