The Explanation
This can be explained as follows. Everything listed before our Mishnah is within the realm of nature. It is all connected to the Creation of the world. Even miracles are within the scope of Creation; they are a part of the "chain" of Creation employing which G-d created (and continues to create) the world. The Holy Temple and the ten miracles that occurred there regularly were also a part of nature, albeit its ultimate perfection. We are taught that Hashem created this world to have "a dwelling place below." One's dwelling place, his residence, is where his actual being is open for all to see. That is where his essence is revealed. "Below" means a world where no one would recognize Hashem's presence within the Creation. A world where we would see the Creation without extrapolating the presence of a Creator.
The difference between our Mishnah and those preceding it is not just a difference in quantity. There is a difference in quality as well. The miracles described in our Mishnah transcend nature. They leave no doubt whatsoever that they are supernatural.
These ten items were entirely and undeniably beyond nature, so they were created on Friday at twilight.
1. Pirkei Avos, Chapter 5, Mishnah 1.
2. Pirkei Avos, Chapter 5, Mishnah 2.
3. See his commentary to Pirkei Avos, Derech Chaim, Chapter 5, Mishnah 2.
4. See Bamidbar Rabbah, Parshas Naso Chapter 16. See also Tanya Chapter 36.
