Knowing nothing much about this there are still some obvious points to make.
The CIA will not be one singular entity of one mind and focus. There will be factions in that organisation, there will be rogue elements. There does not have to be a grand master plan but there could be. There does not have to be uniform competence and there will not be. Operations go wrong all the time. Pieces will be moved into position at vast expense then not used for so many possible reasons. Further if it were a cia operation (and I have no idea about that) it may not have been intended to actually kill anyone and Oswald surprised people by his effectiveness.
All sorts of wild stuff is plausible and you need evidence to assess it. Every huckster will trade on the doubt, there will be wishful thinking and genuine, directed official misinformation. Treating the CIA as an entity all marching in lock-step of one mind and purpose is an assumption that stretches plausibility and certainly requires evidence. Chaos is almost certainly a major factor in any explanation and indeed counts as the entirety of the official version of what happened and its aftermath.
