I was thinking about it more and it occurred to me the important part was about receiving the Holy Spirit. Jesus himself received the Spirit from above, so what he was talking about was an experience he himself had been through.
I found this from a Messianic Jew who explains what the idea of being “born again” meant in the cultural context. I have more understanding of why Nicodemus was confused- the concept of receiving the Spirit of God was limited in Hebrew thought to very high persons such as kings.
Jesus however was no one when he received the Spirit, and only became a miracle-working famous teacher after. The story of Jesus is a few different things. What we are commonly told is what he said- usually the Sermon on the Mount, and usually in an interpretation helpful to progressives. The less common version is about the miracles he performed, more popular among word of faith preachers and usually dismissed derisively by “sophisticates”.
Between the two I much prefer the version about the miracles, having the progressive version of the Sermon on the Mount pounded into my head for years. (It was pounded into my head I had to love the people pounding my head.) But there is another story here too- not what Jesus said, not what he did, but how he was transformed.
Can God be transformed? Can God transform himself? There are other explanations but I think the work of God required that Jesus be transformed from one kind of Son to another. Even the highest born son- since we are using human metaphors- must prove himself to his father, prove that he is fit to rule. He received the Spirit because he was obedient to his father. He became a famous, spell-binding preacher and miracle worker of peerless authority.
But this was not the end. He had to accept the ultimate condemnation and death to perform the work his father really wanted from him. He very much did not want this- he pleaded for any other alternative- but he was obedient to his father’s will, and was transformed, again, further, into he who would sit at the right hand of the father.
It’s a cliché of leadership to say you shouldn’t ask people to do anything you wouldn’t do yourself, but Jesus did it. When he said “Follow me” he meant it literally, not simply to do what he said to do, but to do the things he did.
To receive the Spirit involves I think to be receptive and obedient to God’s will for us, no matter how hard it may be.