Moses taught the Jewish people that the first specimens of their wheat, barley, grape, fig, pomegranate, olive, and date harvests had to be brought to the Temple and given to the priests. The officiating priest would then present the fruits briefly before the Altar and then consume them personally.
We are One
וְלָקַחְתָּ מֵרֵאשִׁית כָּל פְּרִי הָאֲדָמָה . . . וְהָלַכְתָּ אֶל הַמָּקוֹם אֲשֶׁר יִבְחַר ה' אֱלֹקֶיךָ לְשַׁכֵּן שְׁמוֹ שָׁם: (דברים כו:ב)
[Moses told the Jewish people, “When you enter the Land of Israel,] you must take the first of all the fruit of the earth . . . and go to the place on which G‑d will choose to rest His Name [i.e., the holy Temple]. Deuteronomy 26:2

This commandment became operative only after the entire Jewish people were settled in their land. As can be seen in the Book of Joshua, this process took 14 years. Nonetheless, until the conquest and settlement of the land was complete, no one was obligated to bring their first fruits annually to the Temple.

The reason for this is because the ritual of the first fruits expresses our thankfulness for G‑d’s goodness, and as long as there remained even one Jew who had not yet received his portion in the Land of Israel, the people as a whole could not experience complete joy and thanksgiving.

The same applies to us today: As long as there is even a single Jew who is materially or spiritually deprived, the rest of us cannot experience complete joy. The material or spiritual plight of our fellow Jews – and through them, the plight of all humanity and creation in general – should inspire us to action designed to remedy this situation.1