Sorry, some of what you've posted is just fine, but you're pushing your points way too far.
Let's start here:
In 1860 the Southern economy was not nearly as industrialized as the North's, but in the whole world it was second only to the North and small areas of Britain or Germany.
Both Virginia and Tennessee had significant industries which became important in the war effort.
Yes, railroads in the South were not as advanced as Northern, but there were still enough to move products to market, or troops to battle.
Perhaps most interestingly, by 1860 white Southerners were, on average, the most prosperous people on earth, and they well knew it.
More important, they fully understood the sources of their prosperity.
As for their political power, the South had dominated Washington DC politics from Day One of the Republic.
That was due both to the well-earned respect for such Southern leaders as George Washington, Jefferson & Madison, and to the Constitution's 3/5 rule, which gave slave-holders disproportionate representation over Northern non-slave holders.
One result was, before 1860 there had never been an openly anti-slavery President, and Southern Democrats had dominated Congress, the Supreme Court and the military virtually continuously, from the beginning.
As recently as 1856 many Northerners joined the South in electing sympathetic ("doughfaced") Democrats to Congress and the Presidency, giving them almost a monopoly over the Supreme Court.
And that was the rub: with the Supreme Court's 1857 Dred-Scott decision, many Democrat Northerners suddenly found they had more in common with their abolitionist Republican neighbors than with Southern Democrats.
So in 1858 Democrat majorities began to wither, and after November 1860, for the first time ever, both Congress and the Presidency were controlled by Republicans.
But the key point to remember is that the Deep South did not wait for any anti-slavery actions from Washington, DC, but began to organize for secession within a few days after the election in November 1860.
That means they declared secessions "at pleasure", rather than for material just cause, and that made their actions constitutionally illegitimate.
Significant manufacturing capability? Tredegar works in Richmond, VA was the largest manufacturing operation in the entire Confederacy. Half of all Confederate artillery barrels were cast there. It was the only foundry operation in the Confederacy that could cast barrels larger than 3 inch in caliber. It was also the only facility in the Confederacy capable of manufacturing a steam locomotives. There were 5 iron works in the North that exceeded Tregedar’s manufacturing capacity and six more that equaled it. There were some manufacturing operations in the South that could produce rifled muskets at a rate of hundreds a month. The Richmond Arsenal produced at a rate of thousands of rifled muskets a month. But they had to use the machinery looted from the Harpers Ferry Arsenal to do it. The Confederacy had to import rifled muskets from Europe for the entire war, because they could not manufacture enough. In mid 1863 the North stopped importing rifled muskets because the Springfield Arsenal and it 21 contractors could meet the weapons requirements for the Union Army. The South was not even in the ball game when it came to manufacturing.
Your point about Southern political from the Early years of our Republic are quite accurate. But by 1860, the House of Representatives, the Senate, and the Presidency were in the hands of elected officials that were not sympathetic to Southern interests. The perception in the South was that once the Lincoln administration took control of Washington DC, that their would be significant legislation to further limit or end the practice of slavery in the South. The Dred Scott decision aside. That sentiment was a major factor in the deep South States to consider secession as a viable political option.