Given Chinese advancements in drones, a bit surprised that they didn't include any unmanned aircraft in the flying display. Their ground-based tracked drones were also carried by trucks. Would have been cool if they'd had those guys at least driving along autonomously.
All aircraft in the parade flying overhead must be manned. That's just how they set up the parade.
They could have had them flying elsewhere but they've never done a parade where it was in separate locations. Everything had to parade through the Tianamen frontage and everything in the air must be manned for whatever reason. Some are obvious.