Mahasamatman was a human in the far future, the end result of an immortal soul that had been reincarnated hundreds of times. The soul was first born as James Lethbridge-Stewart in 1925, with its first reincarnation in 1951 as Owain Vine.
The soul attended enlightenment and ascended to become the mindless entity that was later called the Great Intelligence. (PROSE: The Forgotten Son)