is the example of Tzipora being Cushit also among the early cases?

Yes, absolutely. Tzipora being called a Cushite is a perfect example of why you cannot understand the Written Torah without the Oral Torah. In the Written Torah, it says that Miriam and Aharon spoke against Moshe concerning the Cushite woman he married. Now, if you just read the text literally, you would think Moshe married someone from Cush, which is the land of black people in Africa. But Tzipora was from Midian, not from Cush. So how do you understand this? The Oral Torah, specifically the Midrash and the commentaries like Abarbanel and Midrash Mepultiel, explain that Tzipora was actually from Midian, which was a neighbor to Cush. The term Cushite here refers to her exceptional beauty, or it's used because of the proximity of the regions. Some commentaries explain that she was indeed a black woman, which also teaches us that being black is absolutely not looked down upon in Torah - the greatest prophet of all time, Moshe Rabbeinu, was married to her, and her father Yitro was one of the most important converts in all of history. Without the Oral Torah explaining this, you would be completely confused about who Moshe's wife really was and what the verse is telling you.