Yeah, the term dreaming is misleading because we think of dreams as insubstantial. For DZ, the Fayth are collectively dreaming the city and everyone in it that a Summoner is channeling to give physical form using gravity and pyreflies.

In the original game, there was no evidence to suggest anyone in DZ was physically modeled on specific people instead of amalgams of several people (which was my view).

In X-2 the presence of Shuyin suggests the possibility that the citizens of could be physically modeled on people that existed in the real Zanarkand 1000 years before. But if Jecht had a specific progenator, he wouldn't be important to the plot of either game.