SLS gave tons of experience, of all kinds imaginable. Like, supercomputers used to calculate aerodynamics, heat-protecting tiles, landing and pacifying procedures, to name some less known. It was definitely not money wasted, even though more than 14 people gave their lives to the program.
Except nothing in SLS was strictly new. The engines are literally re-used, the solid rocket boosters are not new and are 5 segment versions of the boosters used on Shuttle, the tank design is a load-bearing version of the Shuttle. It's all 70s/80s tech at best.
There's nothing new in using supercomputers to compute aerodynamics. It's been done for decades with ever further precision. SpaceX has even done talks that can be found on youtube on it themselves. https://www.youtube.com/watch?v=vYA0f6R5KAI
The heat protection technology is literally the exact same material as used on Apollo, except re-formed into tiles, something SpaceX has been doing with their own heat shielding technology for decades.
The landing/pacifying procedures are variants of Shuttle procedures as the same propellants are used (which are also very old). They're even the same engines and fuel used on Apollo and the Shuttle.
(Also, I do not describe "happened to die during period of employment" as people "giving their lives for the program". That's just extreme propaganda.)
So what experience was gained that was not in the form of "re-learning things that were forgotten"?
