Question: Why do the Jewish people needs a covenant/Brit with G-d. Why do we have to be commanded to follow his Mitzvos? Why is the commitment necessary? Please let me know if you have any suggestions on further readings as well.
Answer: The Talmud asks your question, in a way. First, note that the Torah gives commandments to Gentiles as well, so evidently it is the Torah view that all humans need these. In fact, Adam, the 1st man, was commanded.
Second, you have to define Mitzvah. What is a Mitzvah? You say it’s a “commandment.” I say that’s a fine 2nd-grade answer. An adult definition is “an opportunity to create a spiritual connection to God.”
So you ask, why do I need specific Mitzvot rather than just to create my own? Answers the Talmud: it gives you a greater connection when you are told what to do than if you create your own. This is due to human nature. It is human nature to resist instructions. If I have to overcome that resistance, the spiritual connection is greater.
I don’t have an answer to your other question “why the Bris” but will conjecture that it became necessary as a result of history. Human purpose, and the purpose of all of Creation, is expressed in its most precise way in Torah. At some point in history most of humanity was completely derailed from our mission. When Abraham stepped up to the plate, G-d asked him if he wanted to create a role-model people to light the way for humanity to reach their spiritual potential and purpose. Abraham agreed. The Bris basically means that if we do our part, G-d will respond to us in a way that shows the world that the Torah is true.
I hope that’s a helpful start.