After running through the list of six things (with a seventh likely inserted later), the discussion turns to which of the six was the very first. Of course, they only get through three before getting sidetracked by a new topic - why did the world deserve to be created (or on account of whose merit was the world created).
Here is text and translation of another paragraph in I.IV:
אבל איני יודע אי זה קודם אם התורה לכסא כבוד אם כסא כבוד לתורה, אמר ר׳ אבא בר כהנא התורה קדמה לכסא הכבוד שנ׳ י״י קנני ראשית דרכו קדם מפעליו מאז קדם לאותו שכתוב בו נכון כסאך מאז וגו׳. ר׳ הונא ר׳ ירמיה בשם ר׳ שמואל בר׳ יצחק מחשבתן שלישראל קדמה לכל.
However, I do not know what was first, whether the Torah was before the throne of glory or whether the throne of glory was before the Torah. R. Abba bar Kahana said, “The Torah was before the throne of glory, as it is written, ‘The Lord made me, the beginning of his way, before his works of old’ (Prov. 8:22) – before that of which it is written, ‘Your throne is established from of old, etc.’ (Ps. 93:2).” R. Huna, R. Jeremiah in the name of R. Samuel b. R. Isaac: “The intention (to create) Israel was before everything else.”The last sentence is not really the end of the section but rather the beginning of the new direction the discourse takes. Basically, God foresaw that Israel would accept the Torah; therefore, he went ahead and created the world based on the merit of that decision. Of course, not everyone agrees so the discussion continues with arguments in favor of other candidates whose merit also would have been sufficient to account for God's decision to create.
One of the most fascinating things about rabbinic literature is how much ink is spilled over one line from the biblical text. The text is still interpreting just Genesis 1:1a--"In the beginning God created." They won't even get to Genesis 1:1b until I.XIII.
I don't know what all the fuss is about. It's clear which one came first. Obviously it was the throne because God needed a place to sit as he looked into the Torah and thought about creating Israel.
The Ongoing Series on Genesis Rabbah:
1. Creation in Rabbinic Literature
2. Genesis Rabbah I.I: The Pre-existent Torah
3. Genesis Rabbah I.IV: First Things First
4. Genesis Rabbah I.IV: Identifying Insertions in Rabbinic Texts