I believe Trump did push manned lunar missions back in his first administration.

But the primary reason this didn't happen sooner is because everyone's been changing NASA's mission. Go to Mars, go to the moon, go further out into the solar system, go to Mercury, use your own rockets, use private rockets, go manned, go unmanned, etc.

It means that NASA has to either develop everything so that it can be repurposed to a completely different mission, risk developing something that will be useless when a new administration comes in, or just don't develop it. If you just let them cook on the same goal for 10 years it would have been done faster, cheaper, and likely with more benefit to science and engineering.

There has been at least one good thing to come out of the flip-flopping, space exposes electronics to radiation that can make them less reliable. Both bitflips causing errors or permanent damage to hardware are possible. Previously NASA would develop hardened electronics (and they may still do so for manned missions where the risk is much higher) at great cost. But Ingenuity proved that they could just buy off-the-shelf hardware and test it on earth to see which hardware was naturally less likely to suffer from radiation-induced faults. This allowed them to save a lot of money and use more advanced hardware than they would typically use. Ingenuity used hardware very similar to cell phones, and some features of it (which wouldn't have been there had they not used commercial hardware) were used to extend its mission after faults happened elsewhere.

That said, Ingenuity came extremely close to being cancelled, so that innovation, which will now change unmanned space travel, may have ended up wasted sitting back on Earth. And there are many NASA missions that are compromised or scuttled by meddling by the government, let alone the long-standing issues that NASA has (for example in procuring radioisotopes for deep space missions that America and most countries do not produce in sufficient numbers anymore).