All Christians are equally united to Christ. Ancestry, gender, and status do not matter. All are equal with each other. All are equal in the eyes of God.
Paul uses many different rhetorical questions in this chapter. He uses them to convince the Galatians of their sin. (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/tw/dict/bible/kt/sin]])
This is a complex issue. "Flesh" is possibly a metaphor for our sinful nature. Paul is not teaching that the physical part of man is sinful. "Flesh" is used in this chapter to contrast with that which is spiritual. (See: [[rc://en/tw/dict/bible/kt/flesh]])
Scholars are divided on what this means. Some believe Christians inherit the promises that God gave to Abraham, so Christians replace the physical descendants of Israel. Others believe Christians spiritually follow Abraham, but they do not inherit the promises that God gave to Abraham. In light of Paul's other teachings and the context here, Paul is probably writing about the Jewish and Gentile Christians sharing the same faith as Abraham did. (See: [[rc://en/tw/dict/bible/kt/spirit]] and [[rc://en/ta/man/translate/figs-metaphor]])