This belief that people a 'born' aviators is bolleaux - training and exposure create aircrew so actually you can 'teach ability'.
My major role as a SAR QHI on an operational Sqn was to take pilots just out of the training pipeline and turn them into operational SAR Captains - that doesn't happen overnight, it takes time both to hone handling skills (and teach new ones) and teach decision-making, prioritisation and CRM.
The same happens in all front-line Sqns/OCUs - you take the raw material from the training system - guys and girls who can fly (some better than others) - and turn them into proper pilots.
Most will tell you that although flying training was hard, the real learning and raising of ability occurred after they got their wings.