These are some footnotes from some study bibles that may also help.
JB
19i. An appendix; the author is perhaps making use of a Moabite and Ammonite tradition, cf. Nb 20:23+; these peoples may have prided themselves on having such antecedents, cf. Gen 38. Lot’s daughters are, like Tamar, not here regarded as shameless; their ruling motive is to perpetuate the race. But the Law condemned incest, Lv 18:6-18, and so the story here becomes a gibe at Israel’s foes.
19j. Popular etymologies: Moab is here explained from me-ab ‘from a (my) father’; Ben-ammi, ‘son of my kinsman’, is associated with Bene-ammon ‘the sons of Ammon’.
RSV
30-38: A story which explains the origin of the Moabites and Ammonites, neighbors of Israel.
NJB
j. This appendix reproduces a Moabite and Ammonite tradition; these peoples may have prided themselves on having such antecedents. Like Tamar, Gn 38, Lot’s daughters are not represented as shameless: their ruling motive is to perpetuate the race. v. 31 assumes that Lot and his daughters are the sole survivors of the catastrophe. The story of Sodom, destroyed because of the sins of its inhabitants, may originally have been a Transjordanian parallel to the story of the Flood.
k. Popular etymologies: moab is here explained from me 'ab, ‘from a (my) father’; ben 'ammi, ‘son of my kinsman’, is associated with bene 'ammon, ‘the sons of Ammon’.
NAB
[8] [30-38] This Israelite tale about the origin of Israel’s neighbors east of the Jordan and the Dead Sea was told partly to ridicule these racially related but rival nations and partly to give folk etymologies for their names.
[9] [37] From my father: in Hebrew, meabi, similar in sound to the name “Moab.”
[10] [38] The son of my kin: in Hebrew, ben-ammi, similar in sound to the name “Ammonites.”
NABRE
- [19:30–38] This Israelite tale about the origin of Israel’s neighbors east of the Jordan and the Dead Sea was told partly to ridicule these ethnically related but rival nations and partly to give popular etymologies for their names. The stylized nature of the story is seen in the names of the daughters (“the firstborn” and “the younger”), the ease with which they fool their father, and the identical descriptions of the encounters.
- [19:37] From my father: in Hebrew, me’abi, similar in sound to the name “Moab.”
- [19:38] The son of my kin: in Hebrew, ben-ammi, similar in sound to the name “Ammonites.”