For those will be days of tribulation unseen from the beginning of God’s creation until now: This kind of hyperbole (intentional exaggeration for emphasis) is common in Hebrew and Aramaic patterns of speech. It emphasizes the terror of that time and should not be understood as a precise comparison with every other disaster in history.
and never to be seen again: The events of 13:14–23 would not end human history. History continued after the destruction of the temple in AD 70.