Oswald shot JFK, of that I have no doubt. But he did not act alone, and he probably wasn't the only shot

He just HAPPENED to work in the building JFK drove past. He had only worked there for a couple months. Yet he somehow had enough foreknowledge of the President's schedule, which wasn't published to the extent it is today, to allow him to build a nest, plan and practice his shot, and the motorcade just HAPPENED to slow and take the exact route that would afford Oswald the opportunity.

If JFK had been shot at a speech, on a podium, or somewhere else that was publicized or that would allow for some advance prep, I'd by that Oswald was alone.

But there are too many "just happened to be" for Oswald to have been a lone gunman.