There are many theories on this case.
Would the average person consider them to be far fetched? Would the average assassination researcher/ buff consider them to be far fetched? What about the average scientist or criminal investigator?
I find many theories to be far fetched based on 50 plus years of reading , critical analysis, and common sense. (eg. the defective AR-15, Greer shooting JFK, a person hiding in the trunk shooting JFK, Jackie shooting him, and various religious groups plotting the hit).
It seems clear that other people/ agencies were using the Lee Harvey Oswald name / identity (or a slight variant of it) at various times and in different places.
It seems clear that various alphabet soup agencies had connections to Oswald.
It seems clear that those at the top of the CIA, as well as the military strongly disagreed with (hated is perhaps a better word) JFK and his policies.
It seems clear that LBJ ' political life was saved by JFK's death. The war in Vietnam was also "saved" and millions were subsequently killed.
It seems clear that the mob ( pick your favourite James Cagney name ) could not control the autopsy, Warren Report, MSM coverage, and control of records for 60 years.
Theories dealing with any of the above,either alone, or in any combination may have credibility.