Paul had no slam-dunk argument to prove his position. So he constructed his case using a multi-pronged approach with a series of supporting arguments --- some unique and some overlapping and repetitious.
The culture of Paul’s Galatians was different from that of his Greek and Macedonian converts. And of Paul’s 5 extant letters addressed to his congregations, only in Galatians do we find circumcision as a significant issue.
I don’t think the specific Greek verb Paul used for “having been made” or “having been born” or “having come in being” in Galatians 4:4 is definitive in the argument for or against a historical Jesus. But what is important, I think, is how the term fits within the wider context of Paul’s system, and within the letter to the Galatians.
In Paul’s system, the salvific benefit for humans provided by his Jesus Christ, as well as his Jesus Christ as a model for the wider resurrection to come, are both made significantly more relevant with the pre-existing heavenly benefactor having taken on human form to suffer and die and be resurrected.
“… having taken the form of a servant, having been made (γενόμενος) in the likeness of men, and having been found in form as a man” (Philippians 2:7-8).
In the same vein, Paul’s Jesus Christ as the instrument that freed believers from the Jewish law is made significantly more relevant with the heavenly benefactor having been born under the law.
“... having been made (born) (γενόμενον) of woman, having been made (born) (γενόμενον) under the law that He might redeem those under the Law, so that we might receive the divine adoption as sons. (Gal 4:4-5)
Paul presented his Jesus Christ as a model for the Galatians --- He was born under the law so he could free them from the law --- He was a divine son so, through faith, they could receive divine adoption as sons.
It’s apparent that, for the Galatians, familial relationships were highly significant. Paul dwells on them, promises them, and uses them to drive home his points. The Galatians wanted, above all else, to be sons of the great God of the Jews.
Brothers, let me put this in human terms … (Gal 3:15).
For you are all sons of God through faith in Christ Jesus. (Gal 3:26)
Now if you are of Christ, then you are Abraham's seed, heirs according to the promise. (Gal 3:29)
This leads directly into the passage in question, the imposed chapter division should not be seen as an end to Paul’s use of human examples ---
Now I say, for as long a time as the heir is a child, he differs not from a slave, though being owner of everything. Instead, he is under guardians and stewards until the time appointed by his father. So also, we when we were children, were held in bondage under the elemental principles of the world. But when the fullness of the time had come, God sent forth His Son, having been born of a woman, having been born under the Law, that He might redeem those under the Law, so that we might receive the divine adoption as sons. (Gal 4:1-5)
For you are all sons of God through faith in Christ Jesus. (Gal 3:26)
Now if you are of Christ, then you are Abraham's seed, heirs according to the promise. (Gal 3:29)
This leads directly into the passage in question, the imposed chapter division should not be seen as an end to Paul’s use of human examples ---
Now I say, for as long a time as the heir is a child, he differs not from a slave, though being owner of everything. Instead, he is under guardians and stewards until the time appointed by his father. So also, we when we were children, were held in bondage under the elemental principles of the world. But when the fullness of the time had come, God sent forth His Son, having been born of a woman, having been born under the Law, that He might redeem those under the Law, so that we might receive the divine adoption as sons. (Gal 4:1-5)
I read somewhere (now lost to me) that the first couple of sentences in chapter 4 reflect both Syrian and Roman laws and traditions of inheritance --- Celtic traditions for raising sons also seem to be reflected. Regardless, the passage is a unit, Paul is using a human example to drive home his promise that his Jesus Christ provided both the means for redemption from the law, and for believers to become sons of the Jewish God.
Paul’s letters, and his wider system, certainly contain flaws of logic. No such system is perfect. But the human nature of Paul’s Jesus Christ does not point to a recent human figure, but rather it was a theological construct.
Paul may very well have believed that the Jesus Christ he found in the scriptures had come in human form to suffer and die on the earth sometime deep in the scriptural past --- that we will likely never know.
But here, in the letter to the Galatians, Paul used human examples to drive home his theological points.
robert j