The Midrashim discuss various reasons for the world’s creation: be it Klal Yisrael in general or those who study Torah in specific. Yet there is one Midrash which suggests another reason that is somewhat surprising:
ובזכות בכורים, ומה טעם בראשית ברא אלהים ... ואין ראשית אלא בכורים שנאמר "ראשית בכורי אדמתך."
The world was created in the merit of bikkurim (the first fruit offerings), as it is written, “Bereishis – for the first and foremost thing – G‑d created Heaven and earth.” The word “first” can refer only to bikkurim, as it is written, “The first fruits of your land, bring to the house of Hashem your G‑d.” 
What is the unique significance of bikkurim, more than any other of the 613 mitzvos, that the Midrash understood it to be the very reason for creation?
Each mitzva has its own special segulah and its own nurturing influence on human character, which helps us become finer, kinder people. The influence of bikkurim in particular is to develop the character trait of gratitude, perhaps the most crucial of all traits, without which we cannot possibly hope to develop a healthy relationship with our Creator or with our fellow man.
When a Jew would offer bikkurim in the Beis HaMikdash, he would recall all the kindness Hashem has done for him personally, and for his ancestors before him:
וענית ואמרת לפני ה' אלקיך ארמי אבד אבי וירד מצרימה ויגר שם במתי מעט ויהי שם לגוי גדול עצום ורב. וירעו אתנו המצרים ויענונו ויתנו עלינו עבדה קשה. ונצעק אל ה' אלקי אבתינו וישמע ה' את קלנו וירא את ענינו ואת עמלנו ואת לחצנו. ויוצאנו ה' ממצרים ביד חזקה ובזרע נטויה ובמרא גדל ובאתות ובמפתים. ויבאנו אל המקום הזה ויתן לנו את הארץ הזאת ארץ זבת חלב ודבש. ועתה הנה הבאתי את ראשית פרי האדמה אשר נתתה לי יקוק והנחתו לפני יקוק אלהיך והשתחוית לפני יקוק אלהיך. ושמחת בכל הטוב אשר נתן לך יקוק אלהיך ולביתך אתה והלוי והגר אשר בקרבך.
Then you shall call out and say before Hashem, your God, “An Aramean tried to destroy me forefather. He descended to Egypt and sojourned there, few in number, and there he became a nation – great, strong and numerous. The Egyptians mistreated us and afflicted us, and placed hard work upon us. Then we cried out to Hashem, the God of our forefathers, and Hashem heard our voice and saw our affliction, our travail, and our oppression. Hashem took us out of Egypt with a strong hand and with an outstretched arm, with great awesomeness, and with signs and with wonders. He brought us to this place, and He gave us this Land, a Land flowing with milk and honey. And now, behold! I have brought the first fruit of the ground that You have given me, O Hashem!” And you shall lay it before Hashem, your God, and you shall prostrate yourself before Hashem, your God.
Although a Jew must work to perfect all the traits of his character, the trait of gratitude is the very purpose of creation. Hence the paramount importance of bikkurim, which nurtures this trait. The Ramban writes:
וכוונת כל המצות שנאמין באלהינו ונודה אליו שהוא בראנו, והיא כוונת היצירה, שאין לנו טעם אחר ביצירה הראשונה, ואין אל עליון חפץ בתחתונים מלבד שידע האדם ויודה לאלהיו שבראו.
The purpose of all the mitzvos is to express our faith in our God and thank Him for having created us. This is the very purpose of creation, since there is no other fathomable reason for primordial creation, nor any desire that Hashem may have from His lower worlds, but that man should recognize and thank the God Who created him.
The Targum Yonasan interprets the verse, יהודה אתה יודוך אחיך “Yehudah, your brothers will acknowledge you,” to mean that all Jews will be called “Yehudim” in his honor. The significance of this name was expressed by Yehudah’s mother, Leah, when she first chose it:
ותאמר הפעם אודה את ה' על כן קראה שמו יהודה.
She said, “This time, I shall thank (odeh) Hashem,” and she named him Yehudah.
Our title of “Yehudim” highlights the essence of our collective identity, and our purpose as the Chosen Nation, which is to recognize Hashem’s involvement in our lives, and thank Him for His endless kindness, as we say in the tefillah of Modim:
נודה לך ונספר תהלתך על חיננו המסורים בידך ... ועל נסיך שבכל יום עמנו ועל נפלאותיך וטובותיך שבכל עת, ערב ובוקר וצהרים.
We thank You and speak Your praise for our lives which are entrusted to Your hand … and for Your miracles that are with us each day, and for Your wonders and constant kindness by night, by morning and by afternoon.
Gratitude is the foundation of any healthy relationship between husband and wife, between neighbors, or between friends. It teaches a person to be humble and respectful to those around him, in recognition of how much he owes them. It helps him to be happy with his portion, and happy to be surrounded by people who do so much for his benefit. It nurtures in his heart a sense of love for mankind, and a peaceful contentment with all the good things in life that might otherwise have been overlooked.
In contrast, those whose are ungrateful for the gifts they receive are perpetually bitter about everything they lack, and are at odds with their relatives and friends, whom they resent for denying them the honor or favors they think they deserve.
Gratitude is also the foundation of our relationship with Hashem. In the admonitions of Parshas Haazinu, Moshe Rabbeinu scolded Bnei Yisrael by saying:
הלה' תגמלו זאת עם נבל ולא חכם הלוא הוא אביך קנך הוא עשך ויכננך.
Is it to Hashem that you do this, O vile (naval) and unwise people?
The Ramban comments that the Hebrew word “naval” refers to those who ungratefully repay kindness with injury. Accordingly, this admonition is not so much for the sins themselves, but for the failure to recognize Hashem’s kindness and conduct our lives accordingly. Since Hashem rewards on a scale five hundred times greater than that with which he punishes, we can only imagine the great reward that awaits those who appreciate His kindness, and devote themselves to His service with joy and gratitude. It is thus quite clear why bikkurim and the attribute of gratitude that this mitzva engenders are indeed the very purpose of creation and the reason for Klal Yisrael’s existence.
Another insight into the importance of bikkurim can be gleaned from an episode in the life of David HaMelech. After completing his royal palace, he set his thoughts towards building a Beis HaMikdash, but Hashem forbade him from doing so, saving this honor for Shlomo. The Midrash explains why David did not merit to build the Beis HaMikdash himself:
אתה הקדמת כבודך לכבודי שמשראית עצמך יושב בבית ארזים תבעת בנין בית המקדש אבל שלמה בנך מקדים כבודי לכבודו שנאמר ובשנה האחת עשרה בירח בול וגו' כלה הבית ואחר כך את ביתו בנה שלמה.
You placed your own honor before Mine. Only after you saw yourself sitting in a house of cedar wood did you seek to build a Beis HaMikdash. But Shlomo your son placed My honor before his own, as it is written, “In the eleventh year, in the month of bul (Cheshvan) … the Beis HaMikdash was completed, and then Shlomo built his house.”
From here we learn an important lesson in the service of Hashem. The order by which we arrange our lives reveals our priorities. By beginning the day with prayer and Torah study, we show that our relationship with Hashem is the most important part of our day. For this reason, the Gemara warns so strongly against tending to our own business before davening in the morning, going so far as to compare it to idolatry.
The other matanos kehunah (priestly gifts), such as terumos and maasros (agricultural tithes), are separated only after the crop has been harvested, processed and bought into the warehouse. Bikkurim is unique in that it is marked as sacred from the moment the fruit first begins to bud, as the Mishna states:
כיצד מפרישין הבכורים יורד אדם בתוך שדהו ורואה תאנה שבכרה אשכול שביכר רמון שביכר קושרו בגמי ואומר הרי אלו בכורים.
How are bikkurim separated? The farmer descends to his field and notices the first fig, grape or pomegranate to bud. He ties a cord around it and says, “These are bikkurim.”
Bikkurim thus represent the importance of dedicating our first moments of every day to the service of Hashem, thus showing that this is indeed the most important part of our lives. The same may be said of the beginning of each year, which we dedicate to Hashem in prayer and unity during the Yomim Noraim, thus showing that Hashem’s service is more precious to us than anything else. May our prayers be answered to draw holiness and blessing upon all our endeavors throughout the year.
 Shemos 23:19
 Bereishis Rabbah 1:4
 See Midrash Tanchuma, Shemini 12
 Devarim 26:5-11
 Shemos 13:16
 Bereishis 49:8
 Bereishis 29:35
 Devarim 32:6
 Midrash Tanchuma, Beshalach 21
 Melachim I, 6:38
 Yalkut Shimoni, Shmuel II 144
 Berachos 14a
 Mishna, Bikkurim 3:1