A lot of people criticise the art style of Final Fantasy IX for being way too cutesy, cartoonish and childish. They have large heads, wide hips are generally short. The chibi style characters models are actually an homage to the older games. But the lore of Final Fantasy isn’t just by marketing and nostalgia. From what I’ve learned, when Kitase, Nojima, Itou or Sakaguchi do something, there’s a reason behind it.
So really, why are the characters so short in Final Fantasy IX? In regards to the lore, I think it has to do with the gravity of the core’s planet.
Terra is Gaia’s twin world in Final Fantasy IX. It exists on the inside of Gaia and thus has a blue hue to it, being affected by Gaia’s crystal. Terra is a mysterious world that exists separate of Gaia and of which Gaians are unaware, as even though physical continuity between the two worlds exists, the way to open the portal between the worlds is known only by few.
One clue the Terrans were proportional is Garland himself. I think the Terrans created Garland to look like them. Why was Garland created?
Garland was created to look after Terrans’ best interests and oversee the world’s restoration as most of the people in Terra entered stasis waiting the time Terra would be reborn by assimilation of another planet. Garland himself appears to be some kind of android with an incredibly long lifespan.
Garland is an android, and unaffected by the gravity of the core. Neither are our characters or the Genomes for some reason. But we’re skipping ahead…
The Terrans were unable to find an inexperienced planet to assimilate with, and due to Terra’s crystal growing weaker by the day Garland made the risky decision and chose the young planet of Gaia for Terra to fuse with. The Fusion was a disastrous failure as Gaia’s crystal rejected the process, ending up in the destruction of Gaia’s entire civilization and leaving the planet’s surface in ruin.
Garland began creating Genomes around 3000 years ago so the Terrans could one day be revived. The Genomes were created to one day carry the souls of Terra’s people, but until the planets’ Fusion was to carry out in full, the Genomes’ lives remain incomplete. As Terra’s crystal was diminishing, meaning it would be sent out to the cosmos and die unless saved, Garland devised a plan to control Gaia’s soul cycle.
We could say there’s an anti-gravitational pull inside of the Terran world, so that our characters can move around freely. And as you’ve noticed, the Genomes are the same size as the Gaians. Garland created the Terrans’ vessels to adapt to the gravity of the planets. Gaia has two cores, which means higher gravity. Our characters evolved to be closer to the ground, so to speak.