Black is Beautiful
The Torah relates how Miriam and Aharon criticized Moshe for marrying a Cushite woman. Since Cushis in Africa, and I think it's considered to be Ethiopia, does this mean that the Torah would prohibit or discourage marrying a dark-skinned person? I can't accept that the Torah would have such a prejudice. And what about the Ethiopian Jews today; are they not to marry other Jews?
Before I explain the enigmatic passages that you refer to, let me clarify from the outset that the Torah requires only that a Jew marry a Jew. The complexion of a person has nothing to do with it, other than individual taste. There are many Jews of very different physical appearances, as well as righteous converts from all over the world, and all are free to marry anyone within "the Tribe" as long as the marriage is according to the Jewish Laws of marriage which have nothing to do with skin color.
So what's the explanation of the events you mention?
First of all, we find in the Torah that Moshe married only one woman, and she's identified elsewhere as Tziporah who was originally of Midian: "Pharaoh...sought to slay Moses; so Moses fled from before Pharaoh. He stayed in the landof Midian, and he sat down by a well....Now the chief of Midian had seven daughters...Moses consented to stay with the man, and he gave his daughter Tziporah to Moses" (Ex. 2:15-21). So we see that Moshe's wife was from Midian (in Arabia) and not Cush(in Africa).
In addition, if Miriam's and Aharon's complaint against Moshe was that he married a black woman, what does that have to do with the explanation of their complaint presented in the very next verse: "Miriam and Aaron spoke against Moses regarding the Cushite woman he had married, for he had married a Cushite woman. They said, 'Has the Lord spoken only to Moses? Hasn't He spoken to us too?'" (Num. 12:1-2). What does the fact that they are also prophets have do with the skin color of his spouse?
Rashi's explanation for all this is as follows:
When Eldad and Meidad where given a special prophetic experience amidst the camp (Num. 11:26), Miriam overheard Moshe's wife Tziporah saying, "Woe to their wives if they will separate from them as my husband separated from me". Miriam understood from this that Moshe had separated from his wife on account of being a prophet. She felt this was unjustified and was critical not of Tziporah, but rather of Moshe for separating from her and causing her anguish.
This explains why, after consulting Aharon about whether he also separated from his wife, they both base their claim against Moshe on the fact that they were also prophets, yet neither separated from their spouses. It also explains G-d's response to their claim, "The Lord suddenly said to Moses, Aaron and Miriam, 'Go out, all three of you, to the Tent of Meeting!'" Rashi explains that Moshe, not needing a mikveh as a result of marital relations, was prepared for this sudden communication, while neither Aharon nor Miriam were prepared and suffered a burning need to immerse themselves in water. Since G-d would interact with Moshe at all times with no forewarning, as opposed to them who would have to initiate and therefore be able to prepare for the experience with G-d, they realized the need for Moshe's separation.
But according to this understanding, why does the Torah refer to Tziporah as a Cushite? The answer is that it has nothing to do with her being from Cush. Rather, this is a term used throughout Jewish sources to refer to an exceptional person of distinction. In a non-pejorative way, it's as if to say, just as a dark-skinned person stands out among light skinned ones, this person is "head and shoulders above the rest". (if it were pejorative, it would be expressed as a white-skinned person among dark people – rather the sources compare the dark person to the distinguished individual).
Other examples of this are in Psalms (7:1) where King Shaul is called "Cushben Yemini". The Talmud (Mo’ed Katan 16b) explains that "just as a Cushite is distinguishable by his skin, so was Shaul distinguished by his deeds". Similarly, in Amos (9:7) the Jewish people are called "sons of Cush". Here too the Talmud explains "just as a Cushite is distinguishable by his skin, so are the Jewish people distinguished by their ways from all other nations".