It seems that the British expected the German economy to heavily suffer under their blockade and the latter's exclusion from the global economy, yet not only could Germany finance its continued fight but their biggest issues were a shortage in manpower rather than other resources.
I'm sorry but I'm going to contend your predication that "Germany [could] finance its continued fight" and the implicit claim that they did not have a crippling shortage of both finances and "other resources".
Let's start economically. Germany was financially in shambles by the armistice and it has to do mostly with:
Their economic policies (<--- mostly this)
Their economic isolation from the rest of the world (lead to #1)
Germany had planned for a short war and had the economic policies of a short war, one of massive and rapid borrowing that could not be sustained. While France's credit expanded 242% from 17,289 million francs to 41,937 Germany's would rise 379% from 4,508 million marks to 17,126. Germany would, in fact, have more war loans drives than the Entente Powers combined. She would have a total of 9 while the UK would have 3 and France would have 2, for instance. By the end of the war 90% of the ordinary budget was devoted to interest payments on war debt. So in a very loose sense Germany could (fingerquotes) finance the war but to an unsustainable cost.
It comes down to this: Germany's prime financial issue in 1918 and it's prime virtue in 1914 was its achievement of liquidity. Liquidity is the economic principle of being able to sell goods at their intended value. As in, not having so much overproduction and a lack of purchasing that you don't have to reduce prices to just get rid of it. Borrowing was the major manifestation of this but the rejection of a formal moratorium on these policies was the more important one. They predicted that mobilization would generate a shortage of cash but also leave industry with a shortage of workers and rendering the plant idle, not good. So they flushed their economy full of money to stimulate it. Price controls were good enough in 1914 but as war orders and employment rose Germany needed to throttle back, it was overproducing and overspending. They could have applied harsher taxation or increased interest rates which would have reduced production to a reasonable level and cut back on liquidity issues. They did neither.
Systematic failure of the German government to rethink financial policy for a prolonged war and for long-term employment rather than short term war employment lead to the Darlehenskassen. It would offer an interest rate of up to 6.5% on bonds (as opposed to the Reichbank's 5%) and only required deposits to be fixed for 3-6 months as opposed to years. For the sake of saving you the time of boring financial speak, it was a colossal failure of its intended purpose. In fact the total issue if Darlehenskassenscheine was 15,626 million marks -- ten times the original authorization of 1,500 million. Further instead of relieving liquidity issues of business, it actually pushed business away further. The local governments, who held about 1/4th of the bonds prior to this point rose up to holding an astonishingly 75% while business investments went down.^^1
This allows me to transition into my final point: Resources. The blockade had a noticeable affect on the German economy from a raw and finished goods perspective by the end; this much is fact. Even with the Ukraine under their wing and the war with Russia over with only 1/3 of the grain was given to civilians who comprised 2/3rds of the population; they were rationing what little they had and soldiers were still starving. This list goes on; Germans were eating ~15% of the amount of meat they were eating before the war and that percentage is in the single digits for fish and eggs. Dysentery, starvation, and murder over a few ounces of bread were not uncommon. Germany was a country that relied on imports to survive. A more brief note is the effect the blockade had on war material. Germany was a highly industrious nation but not a nation with a bunch of material at its disposal. By the end of the war if it was a metal park bench, or a church bell, or a guardrail or what have you it was taken and melted down and made into an artillery shell or a rifle action or what have you. They were that desperate.
^^1 Bogart, Ernest Ludlow, War Costs and their Financing, pp. 116-117, Strachan, Hew, The First World War: Volume I: To Arms, pp. 908-911