That's a possibility . One thing about Oswald that is very peculiar is, He used an Italian Carcano riffle. The Italians make very fine things like Ferrari, Versace, Berretta but one thing they are bad at is riffles.
I grew up with guns, My father was Military and also my uncle also Military and an ATF agent. They said the carcano is more deadly as a battering ram like bat..
So its a Possibility Oswald did all those shots but that would mean he is the best marksman ever.
I saw a show on the type of round he used and they said it was possible but 1 in 1M shot.
at that distance its very hard and to make it worse it was a target moving away from him..
I have doubts he acted alone..