While aircraft played a part, a larger part was the US military personnel management practices which enabled them to rapidly build up a pool of good pilots and with the practice of quickly rotating proficient combat pilots back to the states to serve as instructor pilots…further improved the average quality of the US military pilots in the middle-latter parts of the war.
In contrast, the best German/Japanese pilots were kept in the front lines for far longer periods and not rotated back to train a larger pools of reasonably good pilots. As a result, the overall quality of the average Luftwaffe/Japanese combat pilots dropped sharply as the war went on whereas the overall quality of the average US/Allied pilots markedly improved.
A marked contrast to the beginning of the war when Nazi Germany and Imperial Japan had a large pool of well-trained and battle-experienced pilots due to WWI and/or involvements in various wars/conflicts in the '30s like the Fascist intervention on Franco’s behalf in Spain or Imperial Japan’s imperial invasions/attacks in NE Asia and that Soviet-Japanese war border war(Nomohan and Changkufeng) in the mid-late '30s.
Also, keep in mind the Germans had some planes which were arguably better then the best US aircraft…like the ME-262. However, poor long-term planning from the '30s and micromanagement from Nazi bigwigs including Hitler meant those planes weren’t ready in sufficient numbers early enough when their introduction could have made a difference. That and by '44, the Luftwaffe was already suffering a death spiral due to the horrendous attrition of its most experienced combat pilots and the lack of equivalently proficient pilots to replace them.
