What should I do regarding my parents' rejection of my marriage to a religious and kind girl I proposed to, due to my mother's desire for a girl of her own liking, and my parents' rejection of her because of her older age and her mother being from another Arab country?

Allah Almighty has urged kindness towards parents. You must maintain your dutifulness to them and try to convince them of what you want, while clarifying that the quality of religiousness is given precedence in Islamic law, as the Prophet, peace and blessings be upon him, said: "A woman is married for four reasons: for her wealth, for her lineage, for her beauty, and for her religiousness. So, succeed with the religious woman, and may your hands be dusted with dust (i.e., you will prosper)." You can seek help from Allah, then from someone who has a connection and respect with your parents, to convince them.