While the Jaredites were not called Israel, they had still had covenanted with Yahweh, separated themselves from their former associates, and been divinely led to a promised land. Like Ether, Moroni descended from a covenant people who had left an ancestral homeland for a new one. These similarities explain why Ether receives this vision of the future and why Moroni wants to record it. Both men are faithful witnesses that Yahweh will bestow the same blessings on this hidden and unknown people as on the main body of his covenant people.
Moroni relates the vision to scriptures with which he is familiar. Although I date the Jaredite departure after the Israelite exodus from Egypt, I see no indication that they were part of Israel. I consider it unlikely that they would have had any knowledge of the story of Joseph even though they post-dated him. This explanation is therefore Moroni’s. Moroni had the story through the brass plates. Ether could not have known it.
The type depends on the fact that Joseph went to Egypt and never returned. Although the Israelites eventually left Egypt and returned to Israel, Moroni ignores that part of the story and concentrates on the separation that left Joseph in Egypt. The Jaredites and Lehites are therefore comparable to Joseph who, separated from his brethren, became a powerful and righteous people in a foreign land. Then Moroni parallels Moses’s leading Israel out of Egypt and symbolically to Jerusalem. The Jaredites and Lehites will also leave their “separation” and come into Jerusalem. However, it will be a New Jerusalem.