God Valley from Shank's Angle:
1. Garling fell in love with a normal woman on God Valley, and impregnated her. Garling also finds Kaido's Fruit/Joy Boy's Hat (one or the other) on God Valley. The Celestial Dragons love Dragons (look at the Dragon cloning they had Vegapunk doing), and Garling would know about Joy Boy/the Hat, IMO.
2. Human Hunt occurs. Garling offers his Lover the ability to become a CD: loyal to God Valley, Shanks' Mom (S-Mom from here on out) rejects Garling. Garling takes S-Mom as a Slave, as she has no human rights under the WG.
3. Rocks' son and wife are kidnapped by the WG. Rocks kidnaps Celestial Dragon children on God Valley. Imu said kidnapping Kings won't sway Imu: so, Rocks goes for Celestial Dragons directly, their kids. Shanks, Shamrock, and S-Mom are kidnapped.
4. Rocks' wife is killed, and, in rage, Rocks' murders Garling's Lover/S-Mom.
5. Sommers' Dad/Mother are killed in front of him, and out of PTSD, Sommers develops the sadistic urge to force other children watch their parents die in front of them.
6. Kuma teleports Shanks/Shamrock: one goes to Roger, the other to Garling.
7. Garling completely despise normal humans after his lover rejected him/was killed in front of him, and her child became one of the WG's worst enemy's child.