True, going from the Saturn V to the SLS isn't that radical of a jump, but considering all that came in between, the US has made much progress in the last 50 years.
Here's a small (and this is an important word as we've done a lot in the last 50 years) sample of what the US has done:
Build a manned, reusable space vehicle
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Send missions to Mars
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Create the GPS system
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Launch a probe the farthest from Earth a human object has ever been
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Put the most famous telescope in orbit
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We've done a lot in the last 50 years... but so too has China, just not as much:
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The US space program hasn't sat still the last 50 years, it's still the undisputed king that all others are trying to catch. China has made great progress and continues to put the world in awe, but neither NASA, nor US space companies like SpaceX nor CNSA are sitting still.