"39. (alternate formulation) The three keys to keeping a new human space program affordable and on schedule: 1) No new launch vehicles. 2) No new launch vehicles. 3) Whatever you do, don't develop any new launch vehicles."
edit: If we count back to the first successful propulsive landing, the technology was only 5 years old. Falcon Heavy had been planned since way back in 2005.
The central tank is kind of like Shuttle’s, to justify building it in the same factory in Louisiana, but it’s a different diameter, so it had to be a clean-sheet design and all of the tooling had to be created from scratch. The solid rocket boosters are similar to Shuttle (the good Senator from Utah, with all his engineering expertise, required SLS to use solid fuel boosters that only one company in Utah can make), but a different number of segments in length, requiring them to be designed from scratch.
Early in the process of SLS (under its original name, Ares V), a group of NASA engineers lobbied for a true Shuttle-derived version, which would have been much cheaper and quicker to create, with the benefit of lots of flight heritage. Of course they got nowhere, because none of that was why SLS was the way it was. Everything about SLS is designed for the sole purpose of funneling the maximum amount of money to the right contractors in the right states for as long as possible. Thus, it is acceptable that it has never flown even after so many years and so many billions—indeed it’s desirable! If the costly design phase goes on for as long as possible, the money spigot will dispense much more than if it proceeded into operations.
But, just in case, SLS will undergo two costly redesigns after coming into service: a whole new upper stage and new boosters. That should keep the gravy train running for a good long while.
In addition to the Shuttle-industrial complex which must be kept running with make-work, there is now a Station-industrial complex which must receive the same treatment, in the form of an utterly useless lunar-orbit station called Gateway. I’m not sure if you can tell but I’m fairly bitter about all this.
DC-X: First flight (and first successful propulsive landing) 18 August 1993
https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X
"In December 2015, a Falcon 9 accomplished a propulsive vertical landing."
https://en.wikipedia.org/wiki/SpaceX
See also:
https://en.wikipedia.org/wiki/VTVL
Not mentioned in the above link was an amateur group developing VTVL tech around the San Francisco bay area in the 90's. IIRC, it was EPRS. FWIW, they also invented a multi-rotor platform to test their conrol system that evolved into the modern drone.
However, #39 doesn't say “don't ever develop new launch vehicles”, rather “don't develop new launch vehicles if staying in budget and on timeline is your priority”.
And developing their crewed launches has been over a billion dollars cheaper than Boeing, and successfully launched years earlier.
Starship, however, is in fact designed for humans. But it is not part of a "human space program", rather it is a multi-purpose vehicle. It is yet to be seen towards which human space programs it will be applied, but even with the Artemis bid many aspects of Starship were clearly designed without the Artemis bid as a specific target.
What has likely changed is that there is sufficient demand for cargo flights to bootstrap an affordable human flight program on top of it.