Galan Originated From A Earlier Version of Earth-90000000000099, Called Taa. Not Much Else Is Known About His Early Life.
The Big Bang
At Some Point In Time, There Was A Bang Which Almost Wiped Out Taa. So The Remaining members of The Planet Sent Taa, A Space Explorer To Save Taa. He Also Went With A Few Other Members. eventually, They Found The Big Crunch.
Galan Approached The Egg With Caution, But Eventually He Found A Cosmic entity Which Merged With The Mortal, Galan. Making a New Entity, Galactus. The Eater Of Worlds.