There is evidence that Oswald was recruited by US intelligence when he was a teen in the Civil Air Patrol, and that he had gone to the Soviet Union as a false defector (the Soviets did the same to the US). He was part of operation to kill JFK, but then he was set up to be the fall guy behind his back. He claimed he was a patsy before he was he was killed.
If he wasn't working for the government than some of his actions and associations before the assassination are just baffling. It's also a mystery why he was able to return to the US without any issues after defecting.
https://www.kennedysandking.com/john-f-kennedy-articles/1290 https://jfkfacts.org/was-oswald-a-cia-operative-or-not/
When it comes to the patsy argument, read about his interrogation and the cops who interrogated him. The notes are very illuminating. Oswald clearly behaved in a guilty way. Very smug. Remember that his entire life he thought he was destined for something big. He even called his diary "My Historical Diary." He was a loser that needed to do something to be relevant.
I find it very plausible that although most of those things happened, there was no actual conspiracy to kill JFK. Like, there might have been a lot of chit-chat in those circles against JFK and all of what he was doing, but there was no concrete conspiracy to kill him. At the same time, there is this unstable person that seeing and hearing everything that happens around him, believes he will be doing a "greater good" if he killed the president.
Then, the he was silenced mainly because of all the other stuff that he was part of.
It's akin to the time when Trump was president (or Obama for all that matters): There was a lot of chat in the internet and elsewhere about how bad he was as president, how he was damaging the country, yada yada. It would only take one crazy person in the middle of a crazy clique to really go on with it.