>>722938975
Sin whisked Jecht away, further than anyone could travel, by pure coincidental accident. It was a miraculous event of coincidence; Sin was nearby, Jecht was drunk.
Jecht washed up in Bevelle and jailed as a lunatic since he was obviously drunk and screaming "I'm a famous blitzball player from Zanarkand!"
Tidus washed up in Besaid and treated as a "Sin Toxin" lunatic since he had no idea where he was and screaming "I'm a famous blitzball player from Zanarkand!"
The "sea" is never fake. "Dream Zanarkand" is never fake. There is no missing connection. Dream Zanarkand is a real place, out at sea. Sin is a real beast, out at sea. Jecht is a real being, out at sea. Tidus is a real being, dragged out of Dream Zanarkand by his Father/Jecht/Sin and flung out at sea.
Jecht's event was random coincidence
Tidus' event was conspired plot by his father.
This was a MIRACULOUS set of circumstances that led the Fayth (the boy you always see at the temples, remember?) to believe, "We are Dream Zanarkand. We are Jecht. We are Sin. We are Tidus. We can kill Sin, now. Thank God, we can die, now."