In addition to the gifts themselves being symbolic, Jim and Della are also symbolic. The title helps us understand the parallel between Jim and Della and the wise men from the story of Jesus's birth. Just as the original magi brought gifts to Jesus (literally the first Christmas gifts), this young couple gives each other gifts too. But there is a big difference between the original magi and Jim and Della: the original wise men were kings who did not have to make sacrifices in order to bring rich and precious gifts to the Christ child. Jim and Della, however, are quite poor and must sacrifice the things most important to them so each can give a gift to the other. Ultimately, this makes their gifts that much more meaningful and valuable. Thus, the narrator says,
Of all who give gifts, these two were the most wise. Of all who give and receive gifts, such as they are the most wise. Everywhere they are the wise ones. They are the magi.
The narrator suggests Jim and Della are actually wiser than the wise men because they understand love makes a gift truly worth giving. The two recognize the sacrifice made makes their gifts so valuable, not because the gifts themselves are worth a lot of money.