Jesus was to be the Son of David; "There shall come forth a Rod [Jesus] from the stem [David] of Jesse. And a Branch [Jesus] shall grow from his roots [Jesse]" - Isa 11.1.
Then Jesus was predicted to be anointed with the 7 Spirits of God -
Isa 11.2-4; and with the Holy Spirit - Lk 3.22.
"Things equal to the same thing [the anointing of Jesus] are equal to each other."
So then, Holy Spirit = 7 Spirits of God.
And, this was the purpose of the genealogies of Jesus.
Premillennialists say the Messiah is yet to come, but the genealogies were lost almost 1900 years ago.
This too, seems to be a reason for the first century genealogies.
Let the wise man hear!
hoaryhead