Kennedy committed to the lunar landing shortly after Shepherd's suborbital flight, and the idea from NASA was that they'd orbit the moon. Kennedy thought a landing would be more spectacular, but it took NASA quite a while to settle on lunar orbit rendezvous, let alone the Saturn V architecture.
Kennedy was on the verge of cancelling Apollo when he died, and Johnston was anything but a space expert. Johnson was definitely responsible for ensuring no American woman went to space until after he was out of office, the evidence is clear on that one.
The single person most responsible for getting America to the moon was probably John Houbolt (or perhaps Konstantin Tsiolkovsky).
There is also a lot of debate as to whether the ISS has been successful; this really depends on what your objectives were/are.
[1] John Logsdon's Bibligraphy
[2] https://www.nasa.gov/centers/langley/news/factsheets/Rendezv...
I will argue quite firmly that without Johnson, there would be no moon landing or no space program as it developed later and as we know it now.
Johnson definitely did a lot of pork-barreling with the space program funds, but I think the main reason that Apollo went forward was because Kennedy had espoused a grand vision shortly before being shot. Without Lee Harvey Oswald, I doubt that Neil and Buzz would have made it to the moon, especially given Apollo 1.
https://www.fastcompany.com/90376962/if-president-kennedy-ha...
Instead of this, we have the usual situation modern space exploration has settled into, some president boasts that we will do some thing and then after they left office some other president quietly kills it because its way to expensive.
What we should be doing is building coalitions with other countries to do join missions to the moon and all that, thats why the ISS has been so successful, its not just the US or Russia contributing, but dozens of countries. Not to say it could happen without the US or Russia, but the large number of countries working on it helps quite a bit.