A non-sequitur, by definition, lacks a necessary connection to a said event. Yet the Harriet Lane's presence in Charleston was indeed necessarily connected to the bombardment - had that fleet not been sent there, the bombardment would not have occurred! Therefore its presence is necessarily connected, which makes it a part of the battle, and as a part of the battle, it fired the first shot in proximity to that battle.
Hitler could claim that Poles fired first by shooting off flairs on such evidence.
Not really, cause the Poles didn't mobilize at the entrance to Germany to incite a war with Germany.
And as for the territorties. The Civil War started in them long before the official Civil War.
So to you the war "started" with bloodshed in the territories. Does that mean Bleeding Kansas counts as shots fired, but not the Harriet Lane?
To think the Aristocrat slave holders of the South would have stopped the expansion of slavery in the terroritories is a total lie.
How could they have without being clearly invasive upon the territory of another? Sure, you can speculate that they may have been willing to do this, but little beyond that and loose speculation alone isn't enough for you to prove that anything of the sort would have happened.