“Moses.” The Hebrew scribes purposely changed the text from “Moses” to “Manasseh” to protect the reputation of Moses. It was embarrassing to them that the grandson of Moses would be an idolatrous priest. However, the scribes noted the change, which is how modern scholars know about it and many modern Bibles change “Manasseh” back to “Moses” like the REV does. A person can do their best to be godly, but each person decides for themselves whether they will obey God or not.
[For more on Jonathan being the grandson of Moses, see commentary on Judges 18:3.]
“Jonathan...he and his sons were priests.” So Jonathan the young priest got married and had sons who followed in his footsteps.
“the day of the captivity of the land.” This could well refer to the time when the Philistines overran and controlled the land. The verse says nothing about the Israelites being exiled in the days of Assyria, although that is a common belief and may be true. This verse refers to the “land” being captured (or “uncovered”). There was a significant Philistine presence in the Promised Land in the days of Saul.