Orphan is Orphan. Orphan is part of what powers Eden, and Eden was around since long in the past as it powers Cocoon. It was written in the story that long in the past - not the future (and there is not a hint of time travel throughout the story, so we can safely disregard any suggestion on that end) - that Cocoon was made using materials from Pulse. There is no way that Cocoon was created in any time but the past, as to say otherwise would be to render all the stories about the collection of materials and the creation of Cocoon false and pointless, effectively disregarding the plot altogether.

Orphan could not have been created at any time but the distant past when Cocoon was created or even earlier. It is therefore impossible for Orphan to be made up of humans. It should also be noted that fal'Cie are created by Gods, not by fal'Cie. Cie'th are failed l'Cie. l'Cie were created after the Gods had left. Therefore it is not possible that fal'Cie were created from Cie'th or l'Cie, as they did not exist at the time that fal'Cie were created.

Sorry dude, this theory just doesn't have anything going for it. You'd have to come up with a theory that is more in line with the plot of the story. Perhaps you should study the DataLogs for a while longer.