True the CSN performed reasonably well with the resources on hand but excuses don't feed the bulldog. The Secessionists knew that the Southern states were highly dependent on exporting agricultural goods mostly cotton which is heavy and bulky. Heavy and bulky exports require large and slow ships not small and fast blockade runners. The Secessionists should of known they needed a large and powerful navy from day one. That's not Lee's fault but unless the Confedrate Army can seize Union ports at least in the South I e. New Orleans, Norfolk,Port Royal,New Berne etc then the Confedracy can't win the war or at least not likely to. Ultimately there is no excuse for failure.
I think that to argue the Secessionists "should" have known they needed a large and powerful navy is blaming them for something out of their control. They
did know that a large and powerful navy would be greatly beneficial and they took steps to acquire one via overseas purchase and domestic construction, in so far as they were capable of doing so. I'd argue they actually did better with their available assets than the Union did, both in ship acquisition and in the results they obtained.
If the Confederacy could wave a wand and get a navy capable of challenging Union dominance of the sea, this would of course be of immense benefit to them. But it's not practicable, and if you are looking at the minimum requirements for Confederate victory in the Civil War a navy capable of sealane control is a luxury (that is, it is not necessary). The
guerre de course and harbour defence navy which the Confederacy actually employed (and could feasibly acquire without overexpenditure) is a good example of a navy which has been built with limited assets in order to cause as much disruption to the enemy as possible relative to the cost it imposes on the country of origin; at that, many Confederate ironclads happen to have been unlucky in that they would have been fairly cost-effective purchases had the Union not rendered them obsolete by capturing the area they were meant to defend before they had been finished.
The basic role of the CSN is the role of the USN in the War of 1812 - that's the comparison - and honestly the CSN does rather better relative to resources invested than the War-of-1812 USN, if only because the ACW-USN was less capable of defending against commerce raiding than the 1812-Royal Navy. During the War of 1812 insurance rates for British shipping went up temporarily by 30%, with a rebate of a third or more if the vessel in question travelled in convoy, but the convoying system kept the losses from getting out of hand; during the Civil War the US merchant marine took a hammering (resulting in US shipping being unable to turn a profit and being sold at fire-sale rates to Britain) and the USN never did set up an effective convoy system or even a system of stationing vessels in an area that they wanted protected. Their alternative (waiting until news of a commerce raider reached Washington and then ordering ships to converge on the news) meant that a small number of commerce raiding vessels could keep significant numbers of Union cruisers occupied away from the blockade and materially impacted its efficiency.
Given the economic disruption resulting, and given that one of the avenues for Confederate victory is the Union suffering from war weariness, this is an effective use of the CS Navy.
The CSN also pursued avenues to get hold of powerful warships able to confront USN vessels in the open sea (like the Laird Rams) but US diplomacy and British law prevented this from coming to fruition.
With the constraints the CSN was under, and the fact that there was a land connection between the South and the North, I think the level of priority given to the CSN was about right. It's not like having a significant navy was essential for a military victory in this period (heck, the side which won Lissa was the one which lost that war, and the Prussians beat the French on land without really bothering with any naval action) and while Union naval dominance does give the Union a major advantage in strategic terms it's one which the Union very much failed to fully exploit and which wouldn't have prevented a Confederate land victory from being devastating.