His ability to always learn new things is key.
Your sentence, "He makes things impossible for the average person possible." was a little confusing.
May I suggest, "He makes things that are impossible for the average person to do, possible."?
Or, "He makes things possible for himself that are impossible for the average person to do."
Your sentence, "He makes things impossible for the average person possible." was a little confusing.
May I suggest, "He makes things that are impossible for the average person to do, possible."?
Or, "He makes things possible for himself that are impossible for the average person to do."