I recently came across a person that claims to be blessed and person of God, but they're not Jewish, is it possible for someone not Jewish to be a chosen person also?

God loves all of His children whether Jewish or not, and blesses them according to their actions. If this person acts Godly, follows the 7 Noachide laws, then that’s exactly what God wants from him/her and s/he are surely blessed. If this person wants the extra blessing that God promised to the Chosen Jewish People, and wants to receive the entire Torah, s/he is welcome to join, but it’s totally unnecessary, for every Father loves each of His children how they were created!