"May all your creatures be blended together in one united bond to do Your will with a whole heart...
"Our G-d and G-d of our ancestors, rule over the entire world in your glory.... May every product know that You were its Producer, let every creature know that You were its creator...." -- Rosh Hashanah Amidah Prayer
Rosh Hashanah is our New Year's Day, the anniversary of the creation of the world. But when we think of all the possible symbols of this awesome day, we have to ask why a primitive ram's horn is the focus of our celebration of creation. Would not a majestic mountain or a breakthrough sunrise, or even a magnificent product of human achievement, be a far better way to mark the glory of creation than an animal's horn?
Furthermore, if sounding the ram's horn is the essential mitzvah of Rosh Hashanah, why 
Why is the shofar blown by one individual while the rest of us listen?
do its triplicate sounds of tekiyah, truah, tekiyah (straight, staccato, straight) derive from the laws of Jubilee (Leviticus 25:9)? What does the Jubilee year have to do with the creation of the world?

Why is the shofar blown by one individual while the rest of us listen?
do its triplicate sounds of tekiyah, truah, tekiyah (straight, staccato, straight) derive from the laws of Jubilee (Leviticus 25:9)? What does the Jubilee year have to do with the creation of the world?Thirdly, we sound so many times and in so many permutations the three sounds of the shofar on Rosh Hashanah that the sages of the Talmud query: "Why do we blow straight sounds (tekiyah) and broken, staccato sounds (t'rua, nine sobs and also shvarim, three sighs, and also sighs and sobs together) both when the congregation is seated (after Torah reading) as well as when the congregation is standing (during the Amidah - Additional Standing Prayer)? In order to confound Satan!" (Babylonian Talmud, Rosh Hashanah 16a, 16b). What does Satan have to do with all our shofar sounds?
Fourthly, we derive the necessity to sound 100 shofar blasts, and indeed the very definition of t'ruah, from the mother of Sisera, the Midianite general whose mother sobbed through the lattice work of her window as she watched the returning survivors of the vanquished Midianite army and did not see her son amongst them (Babylonian Talmud, Rosh Hashanah 33b). Why link the shofar command of Rosh Hashanah to the sobs of the mother of our archenemy?
Fifthly, one view of the Mishnah prohibits using as the shofar the horn of the "cow" because additional layers grow on to that horn each year, making it appear like several horns ("gildi, gilde." Babylonian Talmud, Rosh Hashanah 26a). What is the problem with a more enhanced horn as a result of the additions?
And finally, why is the shofar blown by one individual while the rest of us listen? The mitzvah could just as well have been for everyone to bring his own shofar, in the way that a lulav is brought by each individual to shul, and everyone would blow the shofars together.
I believe that the answer to all of our questions may be found in a brief incident recorded in Talmud Gittin (52a):

Satan represents strife, disunity, dissension.

"There was a husband and wife in whose home also lived Satan; every Friday evening the couple would get involved in a loud and angry dispute. Rabbi Meir moved in with them, and after three Friday evenings - when he served as referee/peacemaker - he succeeded in bringing peace to the home. He then heard Satan crying, 'Woe is me, Rabbi Meir has expelled me from this house.'"
We see from this story that Satan represents strife, disunity, dissension - the causeless hatred that brought about the destruction of our Holy Temple and which is truly the root of all evil.
Rosh Hashanah is our anniversary of the creation of the world, a world whose creatures emerged from the womb of our One Divine Presence (Shekhinah), a world which must be united if humanity is to endure.
Hence, the laws of shofar blowing are derived from the laws of Jubilee. There is no greater time of unity and peace than the 50th year, when all the lands return to their original owners, when slaves are freed and debts are rescinded. It is a year virtually devoid of social divisions, when distinctions between landowners and serfs, master and slave, rich and poor, disappear. It is a year of social unity.
Of course, we add all possible permutations to unite all the differing customs as to whether the trua is a sighing sound, a sobbing sound, or both together. After all, the most strident and even vicious arguments break out among observant Jews who criticize those with a differing custom as transgressing the law (witness Mitnagdim vs. Hassidim in the 19th Century). Rabbi Abbahu of Kesari certainly confounded Satan when he brought all the customs together by including all possible permutations in the sounding of the shofar (Babylonian Talmud, Rosh Hashanah 34a).
And it's not only unity with the Jewish people, but a oneness between the Jewish people and the nations of the world which we must strive for on Rosh Hashanah. The Talmud, in Rosh Hashanah, quotes a verse in Shoftim as evidence that trua means a sobbing sound, yevava in Hebrew: "The mother of Sisera looked out at the window and sobbed through the lattice." (Judges 5:28) The Jerusalem Talmud says she cried 100 times, and 
Not only unity with the Jewish people, but a oneness between the Jewish people and the nations of the world.
that's why we blow the shofar a total of 100 times. Sisera may be the enemy of the Jewish people, but the pain a mother feels when her son is killed transcends Jewish-Gentile divisions. Rosh Hashanah reminds us of the evil of war, the unity of all peoples in their love for their children, their desire for life and the necessity of peace in the world.

Not only unity with the Jewish people, but a oneness between the Jewish people and the nations of the world.
that's why we blow the shofar a total of 100 times. Sisera may be the enemy of the Jewish people, but the pain a mother feels when her son is killed transcends Jewish-Gentile divisions. Rosh Hashanah reminds us of the evil of war, the unity of all peoples in their love for their children, their desire for life and the necessity of peace in the world.And even beyond the unity of all humans is the unity of all creatures. And the shofar, after all is said and done, is the horn of an animal, a ram. In the sound of the shofar we hear how the very desire for life is something irreducible; it combines and connects and unites every creature of the world. And if Rabbi Aharon Karlier once taught that anyone who cannot say "Shabbat Shalom" to a dog (or a ram) doesn't understand the message of the Sabbath, that is certainly true of Rosh Hashanah, the anniversary of the creation of the world. The universal symbol of the ram's horn must itself be united, without any appearance of separations or divisions.
Yes, Rosh Hashanah is the day when we must blend together in unity with every creature to do G-d's will with a united heart, in order to unify a fractured world.