ASV notes on Genesis 4:19-22
In these verses we meet Lamech and his two wives Adah and Zillah, the son of Adah, Jabal, his brother Jubal, and his half-brother Tubal-cain the son of Zillah. These were not good people, Lamech meant he had the right to kill people for wounding him, because Cain killed the innocent Abel and “got away with it.” They were not good people, but they were smart and crafty. The intelligence and smartness were great at the time of Lamech. The man has not developed, he has degenerated.
Jabal was the first to move his herds and family from place to place for his cattle to always have enough food to eat, and they lived in tents, just like Abraham did. His brother Jubal started the music business, making instruments, lyre, harps, and flute and making music. Their half-brother Tubal-cain became the first smith, and the making of all kind of instruments of bronze and iron started, tools and weapons. At the time of Lamech they were smart and crafty and made the instruments they needed and they enjoyed music when the families came together.