alt Hacker News> yes, maybe you can call the Space Shuttle an "upper stage of a rocket" if you squint hard enough
Why wouldn't it count? It is not the first time in the history of rocketry that the part that is not the boosters returns home intact.
Sure, you can say "it's the first time in the history of rocketry that it lands upright", but you could also say "it's the first time in the history of rocketry that it is not white".
If you want to say how huge this is, tell me how different it is from landing the boosters. Because from the outside it sure as hell looks very similar.
The Space Shuttle has four parts, namely the Orbiter, the External Tank, and the two SRBs. Only the Orbiter is reusable and actually lands, the rest are jettisoned in flight. (SRBs are recovered, the ET is not.) However, the Orbiter is completely incapable of flight without the other three, so it's not a rocket stage on its own, just part of one.
As for why it's harder to catch Starship than Super Heavy, where do I begin:
* Super Heavy is suborbital, its maximum velocity is far, far less than Starship.
* Super Heavy returns upright. The Starship does the famous but aerodynamically very complex "belly flop" to reduce speed.
* Super Heavy only has two static fins to guide it. Starship has four actively controlled fins that need to survive the extreme forces of launch and re-entry.