جَاءَ إِبْرَاهِيمُ — Ibrāhīm came.
جَاءَ: past-tense verb, built on fatḥa.
إِبْرَاهِيمُ: subject (fāʿil), nominative, marked by a visible ḍamma without tanwīn because it is a diptote.
Its function determines the nominative case; its declension class determines the visible ending.