From the Catholic Encyclopaedia, the "first fruits" "sprung up naturally among agricultural peoples from the belief that the first — hence the best — yield of the earth is due to God as an acknowledgment of His gifts. "God served first", then the whole crop becomes lawful food."
The first reading clearly expresses the rationale of the first fruits, "He brought us here and gave us this land, a land where milk and honey flow. Here then I bring the first-fruits of the produce of the soil that you, the Lord, have given me.” (Deuteronomy 26:4-10)
Whether offering the first fruits is still practiced by the people of today or not, we have to realize that the only reason for our existence in this is world is God's benevolence; especially too that he practiced offering his fruit fruit, Jesus Christ, his only Son.
This first week of Lent, let us be conscious whether we would like to offer our first fruits to the Lord or not. The temptations of Jesus are meant to purify our hearts so that the offering of our first fruits would come out more natural and more sincere; they would come naturally from our hearts.
The first temptation highlights our inclination to material possessions. The second, to all the powers of this world, and the third, reputation or our very own pride. All these can be our first fruits if we offer them to God and his work, then we shall be saved; the rest of our lives become a blessing.