They always have this stuff on NPR. I think this is the best explanation from what I have gathered over the years:
1. There's an unspoken rule among world leaders that you don't assassinate each other, no matter how evil you are. It's like nukes...no one wants to start the nuke game because it doesn't end well. When everyone starts assassinating everyone else, the whole system just falls apart. However, JFK & his brother Robert
tried to have Castro killed, and it sounds like JFK's assassination was payback for that attempt. You try killing me, I'll kill you back was the political version of "two can play at this game".
2. There's a lot about the Oswald story that doesn't add up, but the fact is that a dude with a gun shot him, regardless of the background details on how that all came to be. However, based on the latest analytics, it appears that when one of the Secret Service members went to fire back, he accidentally shot JFK at close range in the back of the head instead.
Maybe JFK would have survived the initial gunshot wound, but that closer-range gunshot finished him off, and we didn't want that information leaked to the public because it would have undermined how we were portrayed to the world - it would have been a huge embarrassment if that information got out.
We'll never know what really happened, but I think this explanation makes the most sense - it was initially payback for an assassination attempt on Castro & then a further accident in the heat of the moment that would have made the country look weak to the rest of the world, so everything was covered up.
Or, you know, aliens.