I haven't got an arsenal of quotes, but I just wanna say that I think that whoever else (other than Link) lives in Skyloft are heavily related to the Oocca and the Wind Tribe. Since we are basically agreed that SS is the first in the timeline, I would put it thusly:
1. Pieces of Hyrule break off and form Skyloft. SS happens.
2. Those pieces are restored, or not. Maybe only some of them are restored. Maybe they all are restored to terra firma, but the people who lived there liked being in the sky.
3. Either some people stayed in the sky, or some people return to the sky after some time passes. These would be the Wind Tribe from MC.
4. If you've played MC, you'll know that the people of the Wind Tribe still looked basically just like the rest of the Hylians, but they did have some differences. You could tell just from looking that a person was from the WT. In other words, they were becoming different from the other Hylians.
5. Centuries or millenia have passed, and the Wind Tribe has (somehow, lol) "evolved" into the Oocca. They still have human-like faces, but have developed wings (maybe they used Roc's Capes for a while and eventually just were born with one?). They now live in the ruins of Skyloft. Alternately, if all the broken off pieces were restored at the end of SS, they also developed the technology to build their own island in the sky (possibly more likely, considering how the Wind Tribe lived and built in MC).
This ignores what Shad said about the Oocca creating Hyrule. His statement could be explained by pointing out just how many centuries or millenia we are talking about here. Facts get distorted and/or lost in that time. I would personally say that Shad would have been more accurate to say that "the Oocca are descended from people who were around when Hyrule was first formed."