Who is The Giants from Shikasta: Re, Colonised Planet 5: Personal, Psychological, Historical... and what is their importance?

The Giants are humanoids, They are long-living humanoids and have few children. that have few children. Introduced onto Shikasta by the Canopeans, their purpose is to aid the evolution and improvement of the natives. After millennia, they become accustomed to aiding the Natives, and after the Locke breaks, many decide to stay on Shikasta even though they've been ordered to leave. The Giants die and many of their souls are locked in the nether-regions of Zone Six.