While undoubtedly any ship is better than no ship. Simply building more ships would not have changed the outcome unless they fit into a successful strategy. More battle ships and heavy cruisers would help in small battles, but only more aircraft carriers would help change the outcome of the war. But more aircraft carriers would be useless with out more airplanes. Japan had problems making enough airframes and guns to go in them. On top of this the new Japanese carries carried around 10 planes less then their American counterparts.

More capable escorts and supply ships would also have helped and that has been discussed above.

The Japanese did not understand the importance of their merchant marine, this is demonstrated most clearly by the lack of their attack upon the American merchants. The Japanese preferred to use their submarines in a more direct military role, in the beginning the Japanese had more and better subs but kept most of them close to home and protecting sea lanes. The only effort made to put subs off the US coast was in early 42 and its primary mission was to watch war ships leaving port.

The problems faced in Japan were not limited to naval construction but were rooted deep in the Japanese economy. Post war they sough to learn from the US (the best manufacturers in the world) because everything had been destroyed. This is how they got to be where they are today. Had they won, they would have kept on doing what they had been doing.