One major aspect that the Book of Shemot, Exodus, captures, is the creation of a nation. It is easy to understand that this metamorphosis from a family into a people is an important and necessary development in our national history. What is more challenging to understand is why specifically slavery was the context Hashem chose for that transformation to occur in. In other words, why did Hashem chose to begin his chosen people’s nationhood with slavery?
In fact this question can be formulated significantly stronger. Would it not have been both wiser and smoother to create a nation with a different beginning narrative. Does slavery not come with significant negative side-effects? Looking no further than the Biblical narrative and seeing how much the Jewish people complain, sin and fail, much of which due to their inability to shake themselves from their slave mentally (see Ibn Ezra Shemot 14:13), one must question why this was the Divine plan.
Although many commentaries explain slavery as a result of sin (The Ramban on Bereshit 12:10 points to Avarham’s lack of faith when leaving Israel to Egypt, Shmuel (Nedarim 32a) points to Avraham asking “How will I know that I will inherit it (the land of Israel)” and the Chofetz Chaim points to the brother’s selling of Yosef); but this merely explains why there had to be a punishment, and maybe even why slavery was the punishment selected. These commentaries explain that due to its punitive nature, it was not unjust or unfair, but they do not address why it was ideal. In other words, true, slavery was a punishment, but the transformation into peoplehood could have happened later on in history, in a different geographical place, or in a different context.
Although one can never be completely certain (today without prophecy) or fully understand why Hashem does what he does, perhaps with speculation, one can develop somewhat of an idea; something that gives us some insight and level of understanding.
One potential asset for nation-building results from slavery’s emotional impact. Slavery breaks a person down allowing for a fresh start (Rav Shimshon Rafael Hirsch, 19 Letters, 9). Having absolutely no control of one’s time and destiny results in slaves having no life-direction or self-determination. Freeing them is equivalent to starting a nation completely fresh, empowering them with control over their time and fate (Seforno 12:2, Rav Solovetichik).
Yet in addition to offering a fresh start, another important aspect emerges. Servitude facilitates an easier transition to serving Hashem, cultivating unwavering commitment and dedication. No one knows obedience like a slave. Emancipation couples slavery’s commitment with freedom’s self-determination and direction.
Perhaps a second advantage may be the exodus’ enabling Hashem to display his greatness and majesty in an unprecedented and never-repeated manner. Hashem did not merely completely undermine atheism and deism, as the Ramban (Shemot 13:16) notes, Hashem completely discredited the popular and then contemporary theological belief of polytheism in the world’s most respected aristocracy at the time, Egypt.
Hashem did not merely command that particular generation’s respect, but through Mitzvot (commandments) designed to remember what occurred, he commanded and continues to command the respect for all generations (Ramban ibid). This could have only happened in Egypt which contained both a nation deserving punishment for a severe crime, like enslaving with great cruelty the Jewish people, as well as the world’s aristocracy, for their admission to monotheism carries more weight than anyone else's at the time. Perhaps this is at the hart of the Midrash (Shemot Rabbah 16:3) that records that Hashem would not allow the Jews from being sent, until they slaughtered the Egyptian God before the Egyptians eyes. Clear theological victory was necessary.
However, perhaps Egyptian slavery offered a third element. Imagine how great a Kiddush Hashem (sanctification of Hashem’s name) it would be if in one generation after slavery the Jewish people embodied the values of the Torah and rose to spiritual greatness. Imagine the enormous respect and honor the Torah would be crowned with if the world saw how it transformed the Jewish people from the lowest spiritual (the 49th) and social levels to the highest. Ultimately that is an enormous goal of the Torah, to help the Jewish people cultivate proper religious values and ideas.
If the generation of the exodus did not repeatedly fail, that feat could have been accomplished in one short generation. Slavery was a means to help illustrate the incredible power and impact the Torah can have on the Jewish people.