You are correct. The big brass had decided that the Pacific war was less important than first defeating the Germans. If the Japanese had known what materiel and other resources the Americans (and the Brits and the Australians) were going to throw at them, maybe they would have not launched the war.
Not only did we have far more men and materiel, we had much better materiel. The Japanese weapons were far inferior by the end of the war to ours. Even the Zero, which outclassed all American fighters at the start, was outclassed and severely outnumbered by the end. Japan simply didn't have the manufacturing capability or other resources. Their troops had great esprit de corp (even WWII ex-Marine William Manchester, who still disliked Japan years later, admitted that no soldier was braver than the Japanese soldier), but that wasn't enough.
The Japanese did know that they could not compete, at least on the long-term. Yamamoto had spent some time in the USA. If he had achieved all of his objectives, he might have forced us to take a defensive posture in the Pacific, IF he could have taken the Solomons and if at Pearl he had hit the fuel reserves, the war would have taken on a different complexion. If we had not raced the Germans to get the A-bomb, we probably wouldn't have developed it. The Japanese became the victims by accident. Contrafactual history: If Hitler had not attempted the Ardennes Offensive, he might have held us at on the Rhine while he threw his reserves against the Russians. The war would have continued until we exploded the first Atomic devise. We would then have broken the Germans by dropping the two a-bombs on them.