I thought it was remarkable that she’d call the Earth her planet, since Amethyst is the only known Crystal Gem to have actually been made on Earth (besides Steven of course). I always found that Garnet saw the humans more as equals than Amethyst and especially Pearl did, but with the recent clips from SDCC, we’ve gotten information that finally made me understand!
In the longer version of the Title Song, Garnet sang:
“I will fight for the place where I’m free! To live together and exist as me!”
So excuse me if I’m wrong, but I came to this conclusion:
EARTH WAS WHERE RUBY AND SAPPHIRE FUSED FOR THE FIRST TIME. IT’S WHERE THEIR LOVE FOR EACH OTHER TOOK A PHYSICAL FORM. IT’S WHERE THEY COULD FINALLY BE WHO THEY WANT TO BE. EARTH IS THE BIRTHPLANET OF GARNET.