A better way is to teach basic concepts (such as which bodily weapons are best against each body target, which ways you may bend a foot, wrist, or arm to cause pain, how to create openings in the opponent’s defenses, etc.). Then these basic concepts are used in an instinctive response to the opponent’s actions and reactions. Instead of using a specific action in response to a specific attack, you use whatever response may be best for the situation. Other instructors have different opinions on the subject.
One may be an all-around good athlete and still not be good at Taekwondo. It is okay to be good at many sports, but it you want to excel in a particular sport, you must be good in things that help you achieve excellence in that sport. To excel in Taekwondo you need to do things that better your ability to perform Taekwondo techniques and movements. Running and swimming a lot will have some beneficial effect on your Taekwondo training, but they mostly make you better at the motions needed in running and swimming, neither of which is particularly useful in Taekwondo, except running when it is used to exit a self-defense situation. Performing a lot of Taekwondo techniques and movements will make you better at Taekwondo. Training in the bodily motions that are specifically used in Taekwondo will make you better at Taekwondo.