It looks to me like many people, maybe most people including most Christians and Muslims, think that the Quran denies that Jesus was the Son of G_d. I think that the Quran denounces the idea of Mary being the mother of G_d and/or the mother of G_d’s Son, but I don’t think it denies that Jesus is the Son of G_d in the way that the Bible says He is, meaning that He is king of Israel.
In the time when the Quran was revealed people might have been saying or insinuating sometimes, as they do sometimes today, that it is the way Jesus was born that makes Him the Son of G_d, and also that it makes Mary the mother of G_d. There might have been a need for G_d’s purposes at that time to denounce those ideas unequivocally, without confusing the issue by affirming that in a certain way Jesus really is the Son of G_d. That might be why the Quran says repeatedly that G_d “does not beget, nor is He begotten.” “G_d does not beget” means that Mary is not the mother of G_d’s Son, and “nor is He begotten” means that Mary is not G_d’s mother. Saying that in a certain way Jesus actually was the Son of God would have been needlessly confusing and distracting.
I think that the king of Israel was sometimes viewed figuratively as the son of G_d. The difference between Jesus as king of Israel and the other kings might be analogous in some ways to the difference between a begotten son and an adopted son. For example, the other kings were anointed by a priest, but Jesus was anointed by G_d Himself. However that may be, the way He was born does not make Mary the mother of G_d, or of His Son, and that might be the whole point of the Quran saying that G_d “does not beget, nor is He begotten.” Not to deny that Jesus was the Son of God, meaning the rightful king of Israel.
I’ll be doing some more research on all that. I would welcome any scripture references that anyone thinks I’m contradicting.