You missed the word “misconstruction”, to wit: we didn’t mean for the feds to have a certain power, but someone managed to concoct it out of the Constitution’s wording anyway.
Nothing in the Constitution was intended to give the feds any power to disarm the people (or prohibit any inanimate objects), but eventually the political desire to do so deliberately misconstrued the “commerce clause”, along with the general power to legislate, into rationalizing that power into existence.
I forget the exact court case, but the judge made a salient point. He said the natural state of commerce was free and unfettered. ANY regulation, therefore, was a restriction.
So the power to regulate is the power to restrict, even to the point of prohibition.