1 - It's not proven beyond a reasonable doubt that Oswald fired a rifle on 11/22/63 or was even on the 6th floor at the time JFK was shot.
There is some direct evidence. But the circumstantial evidence is enough to convince a reasonable person that Oswald was on the 6th floor and fired all three shots. The evidence of what he did afterward speaks volumes. And the evidence that he fired a shot at Gen Walker's head constituted similar fact evidence of the most cogent kind.
2 - Ruby was affiliated with the Mob. The Mob hated the Kennedys. Ruby owed debts at the time of the JFK assassination.
Ruby was a nightclub owner who carried a gun and liked pistol whipping the odd patron who touched his employees inappropriately. There is innuendo but no hard evidence that he was affiliated with "the mob". Besides, the Mob disliked Bobby Kennedy more than Jack. And Frank Sinatra was a good friend of the President.
3 - There's not enough evidence to rule out multiple shooters and the physical evidence is flawed. Several books have been written detailing the problems with the evidence.
There are always little problems with evidence. That does not amount to evidence to the contrary. There is no evidence of another shooter.
4 - The HSCA's bullet analysis linking all the Dealey Plaza bullet's to Oswald's rifle has been debunked too.
Are you referring the the NAA analysis? I will agree that the comparative bullet lead analysis has been debunked. But that just means that it cannot be shown that the fragments all came from the same bullet. The shells came from the MC but the only bullet that can be positively tied to the MC is CE399.
5 - Even among those who think Oswald acted alone, there's no consensus on Oswald's motive. No proof that he opposed or even disliked JFK.
True. But Oswald was an impulsive person. How many people do you know who shared his political views actually gave up their citizenship and moved to Russia? How many people who disliked Gen. Walker took a shot at him? How many people took a longish package to work on the morning of Nov 22/63 and had their palm print on a package in the sniper's nest? Oswald was probably depressed and angry at the world because he was working for $1.25 an hour and had to support a wife and two young children. Not everything that such people do is always rational or well thought out.