James Ellroy’s AMERICAN TABLOID is still the most fun version of the JFK conspiracy universe. But I do think it’s been well estabished for a long time that L.H. Oswald shot him from the school book depository building. From that vantage, with that rifle and the clear, slow-moving target in the limo, a shooter could hardly miss.
You must have never hunted then. One shot-yes, two shot-maybe, three shots-unlikely, very lucky, and not probable. I guess Ruby killing him is not big deal.