Is repeating Qur’anic verses due to admiration for the reciter’s voice or his recitation style, and not for the purpose of contemplation, while continuing to hum them to oneself as one used to do with songs previously, considered an abuse of the Qur’an or likening it to singing?

Congratulations on abandoning listening to music and engaging in memorizing and listening to the Qur'an. There is no harm in a Muslim repeating a verse out of admiration for the reciter's voice or manner of recitation, provided that the reciter is proficient in recitation and observes the rules of tajwid and voice beautification. This is because listening to the voices of reciters known for their beautiful voices is permissible in Islamic law. The Prophet (peace and blessings be upon him) loved to hear the Qur'an from his Companions and encouraged beautifying one's voice with it, as he said to Abu Musa al-Ash'ari: "You have been given a mizmar from the mazamir of the family of David." It is important to note the necessity of reflecting upon the Qur'an when reciting and listening to it.