Lucas knew he was making the story up as he went but created a false mythology for fan worship that he had the whole 3 trilogies in his head since day one.

Then it became only six movies about the story of darth vader now made false because of sequel trilogy.

He could have just admitted having no omniscience over star wars but his godhood status would have been threatened for this self made star wars cult in which Lucas oversaw and created everything.

He once did claim it was all a collaborative thing and gave thanks to the others involved as late as receiving the Irving Thalberg award.

On the prequels i don't think he wanted to be challenged and brought in a whole new team to oversee his vision. From the young indy series. except of course he still had Dennis Muren and Ben Burtt from the original series.

He also brought back John Williams, and Tony Daniels to voice C-3PO.

Okay so he brought back a handful of the original players in the OOT. But none of the writers or directors, producers/cinematographers.