We need to step into the "way back" machine and look at what was going on back in the 50s and early 60s...
The Cold War was in full swing, a hot war if you consider Korea and the Russian and Chinese involvement against the Americans. Rocket technology was growing by leaps and bounds, IRBMs were being developed and deployed. Larger rockets were being developed.
The first Earth satellites were launched. The Russians beat the Americans with Sputnik, partly due to the government's reluctantance to use a military booster (Redstone) for the First US satellite. Eventually , after the Vanguard failure, the modified Redstone was used to launch Explotrer 1, the world's first real scientific satellite. It discovered the presence of the Van Allen belts.
The space race caught the attention of the public, and both governments made great use of this competition. Funding for rocket programs grew, and inevitable the plans for putting men into space evolved. Eisenhower created NASA. The Mercury 7 astronauts were selected. Plans for adapting the Redstone and Atlas for manned flight were underway. The American people were caught up in the program. And they didn't want to be second to the "Reds".
The Soviets indeed scored many firsts. The US program worked to perfect their spacecraft, building them with unique capabilities. Fuel cells, the ability to change orbits were very important US firsts.
The question that needs answering is "why would they fake the landing missions"? It would have to be a physical or technological barrier which could not be overcome. There were plenty of technical issues which no doubt evoked a "how in the hell are we supposed to do that??" response. Building a 3000 ton, three stage rocket to launch the stack to the Moon comes to mind. The LM, fragile and "flimsey" is another. But real enginers, using real materials and knowledge, worked the problems. The line guys were designing and building ships that would accomplish the mission. They knew the stresses, the forces, the environment they were building to withstand. They were building spacecraft that would work. Technology was growing by leaps and bounds.
The Van Allen belts...numerous probes were exploring the region, studying the size and radiation inside the belts. They were pretty well understood, and the knowledge was growing. Planners were confident they understood the problem and plans to mitigate the radiation were incorporated, through trajectory and spacecraft design. The trans lunar and lunar environment were also being examined. The Pioneer craft, Ranger series, and Surveyors studied the space out there, and the lunar surface, through flybys, orbits, and landings. Slow, methodical progress. This was all critical data that needed to be understood before humans ventured out. The data was coming in.
The Gemini program proved that rendezvous and docking could be done with precise orbital mechanics calculations. Space walking was maturing, after several shakey attempts. And the big Saturn was progressing.
All of this was real. There may have been potential motives to fake something for publicity or politics, but it wasn't necessary. The craft were working.The Saturns flew...not perfectly, and the problems were identified and solved, but they flew. No need to fake anything.
There were no insurmounable environmental or technical hurdles that prevented Apollo from going to the Moon. Were there risks? Yes, far more than today's risk averse society could stomach. But it was do-able, with contingincy procedures built in every step of the way. The Sun could flare up, the SPS could fail, the SIC could pogo itself to destruction. And people could die, in pursuit of a great dream.
But they didn't, and we have a great historical acheivement, taking humans to another body. There was no reason to fake it. That would have been far more hazardous to national prestige than just being "second" to the Russians. And I don't think there would be anyone that would want to do that, it just wasn't how we did things. Hundreds of thousands of workers made it happen, they wouldn't have tolerated it. They were building real spaceships, and were fiercely proud of what they were doing.
It was a race, and pressure was great to meet Kennedy's deadline, and to beat the Russians. The Saturn's second stage was behind schedule, with numerous technical issues. Folks were fired, management reshuffled and experts poured into the plant to help solve the issues. The LM suffered the same kind of challenges. The problems were worked, nothing went "smoothly".
I'm rambling now, but you get the drift.

