I highly suggest people go watch "inside the book Depository" [1]. It's long but it gives a good overview of the sequence of events and the discrepancies.
Thing is, it's not a conspiracy theorist video. The best part of the video is the last segment where the creator uses all the examples to show just how unreliable eyewitness testimony is, even when fresh let alone decades later. They go on to say that pretty much any conspiracy theory relies on cherry-picking certain details as irrefutable while ignoring others and this is esentially an arbitrary decision based on whatever narrative someone is pushing.
Additionally, the details supposedly changed never make sense for a conspiracy that is supposedly powerful enough to arrange all this.
Lastly, people often see things through a modern lens. Presidential security is a big one. JFK used to stop his motorcade and go into the crowd. Anyone with a handgun could've ended him. These people weren't all frisked and vetted. It was a different time. JFK's assassination is probably a big part of why presidential security changed. So the idea that you needed to have or be a sniper (or a team of snipers) is a silly one and based on modern assumptions.
Myths in this area persist too despite them being debunked. One that springs to mind is that you couldn't fire Oswald's rifle fast enough. CBS and the FBI tested and debunked this in the 1960s [2].
When this happens you'll often find the conspiracy theory moves the goalposts from it being "impossible" to "very hard". I'm sure it was hard but Oswald was also irrefutably a Marine-trained shooter.
Personally my theory is that any mystery surrounding JFK is much like that of 9-11: intelligence agencies caught with their pants down, not wanting to upset allies and/or not wanting to expose intelligence assets.
The last point I'll make is a study was recently done on the link between narcissism and conspiracy theories [3]. Now this has a lot of relevance to why who gets sucked into QAnon and their political leanings. But it's relevant beyond that.
A lot of people are uncomfortable with the idea that random things happen. They'd rather believe it's all part of a plan. It's almost preferable if it's a nefarious force as some people love to LARP as being oppressed or even just being brave warriors standing up for what's righteous. But this shares a lot of the psychology with those for a predilection for religion. And narcissim is the definition of main character syndrome.
[1]: https://www.youtube.com/watch?v=5u7euN1HTuU
[2]: https://en.wikipedia.org/wiki/John_F._Kennedy_assassination_...
[3]: https://pubmed.ncbi.nlm.nih.gov/35816915/