I share your frustration regarding our recent history in space. It goes back to the end of Apollo. The country quickly lost interest and they even had to do the Space Shuttle program on the cheap. (Full disclosure: NASA was a client of mine in the effort to return to flight after the Columbia incident.) I also know they could, if properly funded, prepare a new set of crews while simultaneously creating a vehicle for them. In fact, having the crew in place and engaged would likely spur development, as it did in Mercury, Gemini, and Apollo.
12000 apply https://www.space.com/nasa-receives-over-12000-astronaut-applications-for-artemis-generation.html
This thread has me interested in learning about the history of NASA and space flight. Might anyone be able to recommend a book for me to read on the subject?
Through the Mercury program, yes. But it is a narrative more focused on the astronauts and their wives, rather than a straight history. Also, there is a lot of stuff on test pilots (the ones with the real "Right Stuff" like Yeager and Crossfield.
Here’s what I did. Google “history of NASA” and no surprise, you get a hit on the NASA Wikipedia page. Toward the end of the article you’ll find all the references. These include all sorts of history books that I’ve never heard of before. I’ll bet one of them will be what you want.