By design, none of the Final Fantasy games connect. However, the one constant of the old school Final Fantasy games remains the Crystals. The Crystals have been in every mainline series game, in one form or another. Of course, only in a few odd numbered mainline series do they appear as the reason behind the job classes. And we see a steady evolution of the job classes with each iteration. So what if there were a connection between them? In what way would they connect? Chronically, in the original order of release: Final Fantasy I, III and V.
This would be similar to the chronological ordering of Final Fantasy II to IV, or Final Fantasy IV to VI. In those games, the supposed connections happen through characters (Ricard, Kain) or events (War of the Magi). Here, the connection is through the jobs.
The job class would begin with Final Fantasy I. These jobs correspond to the original heroes who defeated Garland/Chaos. The Crystals would record their heroic exploits and the power of the jobs. Sometime later, other heroes with specific jobs would arise holding crystals. They would have to face whatever cataclysmic event caused parts of a continent to float. These jobs would be available for the four orphans, or Luneth, Arc, Refia, and Ingus.
Sometime after the Cloud of Darkness’ defeat, the Floating Continent would rejoin with the Surface World, yet separate again. More warriors would challenge and defeat Enuo. These worlds would be Bartz’s and Galuf’s worlds, which would mean the Merged World is World A.
Ironically, the lore explaining the formation of the world would tell the cosmological story backward.
Final Fantasy V:
In the beginning there was Void. Then four spirits came together in this Void.
The crystals were born and the world was created.
Thus, Hope gives the earth blessings, Courage lights the flames,
Kindness makes water the source of life, Pursuit lets wisdom ride the wind.
When the time comes that Void shall again envelope the world.
if within people live the four spirits, Light shall again be born.
Four spirits, Wandering through Void Shall once again give birth to light.
Final Fantasy III:
The earthquake was only the beginning. The great tremors that swallowed the crystals, the light of our world, only to spawn monsters from the depths of the scarred land, are nothing but harbingers of what has yet to come. Something is coming…fathomless, ominous, and full of sorrow… But hope is not yet lost. Four souls will be blessed with light, and so it shall begin.
Final Fantasy I:
The world is veiled in darkness. The wind stops, the sea is wild, and the earth begins to rot. The people wait, their only hope, a prophecy….When the world is in darkness Four Warriors will come….After a long journey, four young warriors arrive, each holding an ORB. -The introduction.
We can see that the world map is somewhat similar in all three, with minor differences. We can explain the differences by the geographical shifts that occur after every cataclysmic event.