An amazing claim, but this is not the first time in the Torah it is made. Moses already said a similar thing at the beginning of his final message in Deut. 8:4.
Rashi suggests that the clouds of glory that accompanied the people on their journey rubbed the dirt from their garments so that they always looked fresh and new, and as the children grew up, their clothes grew with them.
Ibn Ezra quotes a view that they brought many changes of clothes when they left Egypt; another view was that the manna they ate in the wilderness did not make them perspire and so the garments lasted longer.
Other commentators say that this was one of the Divine miracles; just as God watched over the people to ensure their safety, so He ensured that all their material needs were met.
On the verse, “Your clothes did not wear out”, Hertz comments, “You had no need to trouble yourselves with material cares” (One cannot be certain whether Hertz realised there was a double entendre in the word “material”!).
Whatever the correct interpretation, there is a lesson for our generation which seems over-concerned with clothes and shoes, with fads and fashions, with appearance and attractiveness.
Not that halachah believes in being dowdy; one should always dress smartly and neatly (and modestly), and the sages warn of the dire consequences if a talmid chacham has specks of dirt on his clothes.
But more important than constantly being concerned about what one wears is to work on one’s mind and character and to take to heart the words of King Solomon, “Charm is deceitful, and beauty is vain, but a woman who fears the Lord, she shall be praised” (Prov. 31:30).