All about trying to beat China?
I don't think that's true. Basically all missions are "low earth orbit", unless you create a GIANT rocket... like the Saturn V. The US did this for the Apollo mission; however, even though they have the blueprints, the rockets literally cannot be made any more because it was designed for a different workforce with different skills.
There's also many advances in computing and engine technology to incorporate. And getting all correct is hard.
The Soviets were never able to create a rocket comparable to the Saturn V. They tried, it blew up spectacularly, and ended their space program. It was "cowboy engineering"... not the cautious incremental stuff that NASA did with Saturn V.
China is building the Long March 9 and Long March 10 rocket systems, and that's awesome. However, NASA is building the capability because they do not have it at all, and they want it for Mars/Asteroid/Moonbase missions. There's genuine interest in the USA to do this.
I assume the Chinese will do a much better job than the soviets, and actually get their rockets working. They're way behind NASA though. The first SLS mission is targeted for Feb/2026. The first Long March mission is expected to be 5-10 years later (!). So hardly a competition for who gets there first.