In this discussion qadīm means a being not preceded by nonexistence; ḥādith is the opposite, one that comes to exist after not existing. Continued duration asks something else: an entity can begin and thereafter endure without becoming beginningless.
Imagine a building that remains standing for a very long time. Its durability does not erase the fact that construction had a beginning. This is only a conceptual illustration; the relation of God to creation is not identical in every respect to human manufacture.
Thus everlasting duration and beginninglessness must not be confused. The question here concerns the world's temporal commencement.