Deuteronomy 32:10-14 sings about the exodus and occupation of the land as events in the past. So Moses doesn’t seem a likely author. But how far in the past do the events need to be? Verse 32:15 seems to me to look back on a period of prosperity in the recent past. There could have been such a time during the period of the Judges, but our record doesn’t have one that stands out.
The most outstanding time of prosperity would have been the reign of Solomon. This leads me to suggest a historical interpretation of verse 12:
“The LORD alone guided him, There was no foreign god with him.”
When Solomon died, the northern tribes seceded from the Jerusalem-led kingdom (1 Kings 12). Jereboam became king at Shechem in the north. In order to undermine the temple at Jerusalem as the politico-religious center, he made worship centers at Dan and Bethel for his people. He used bull or calf icons somehow in these sanctuaries. He probably considered them no more idolatrous than the cherubim iconography at the Jerusalem temple. But he seems to have given them a historical interpretation:
“See your gods, Israel, who brought you up out of the land of Egypt” (1 Kings 12:28).
Now the bull iconography probably had something to do with the popular Phoenician fertility religion and the sympathetic magic that people thought made the crops and herds grow. Phoenicia was closely connected with the northern tribes of Israel. But Jereboam claimed icons like this had been with Israel in the desert, on the way from Egypt. (At Timna there had been a shrine to the Egyptian cow goddess, Hathor. Could this have been the origin of idea that some kind of bovine deity was in the desert with Israel?)
Deuteronomy 32:12 flatly contradicts this. There was only one deity guiding Israel in the wilderness, the LORD.
The point here for spirituality is the description of the tender care God gave his people in the desert. He encircled and cared for Israel (v. 10). The “apple of his eye” in verse 10 probably should get translated as the “pupil of his eye.” The sense would be that God cared for his people as one would care for his own eyes.
“Like an eagle that stirs up its nest, that flutters over its young, spreading out its wings, catching them, bearing them on its wings” (Deuteronomy 32:11).
Whether the eagle was meant to contrast with the bull at Bethel and cause people to think of the winged cherubim at Jerusalem, one can only ponder.