Matthew 3:13 Then cometh Jesus from Galilee to Jordan unto John, to be baptized of him.
14 But John forbad him, saying, I have need to be baptized of thee, and comest thou to me?
15 And Jesus answering said unto him, Suffer it to be so now: for thus it becometh us to fulfil all righteousness. Then he suffered him.
16 And Jesus, when he was baptized, went up straightway out of the water: and, lo, the heavens were opened unto him, and he saw the Spirit of God descending like a dove, and lighting upon him:
17 And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased.
See also Mark 1:9-11 and Luke 3:21 & 22
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To someone who considers the God of Moses to be creator of everything in the material universe, every human is a child of God in the sense of being created by him. Adam and Eve were children of God in yet another sense: They had no human parents.
People who are learning to trust the Lord are children of our heavenly Father in the way described in the Gospel of John. “But as many as received him (the true Light, which lighteth every man that cometh into the world*), to them gave he power to become the sons of God, even to them that believe on his name: Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God. - John 1:12 & 13 (*verse 9)
In the sixteenth century, King James I of England commissioned translators to create a new English translation of the Bible. When they referred to the way all humans are children of our heavenly Father or to the way believers are his children, the translators didn’t capitalize the word “sons” (employed in the inclusive/generic sense of the word).
The translators considered Jesus to be the Son of God in a sense that nobody else is. They indicated their belief on this subject by two things. When the text was a reference to Jesus, they used the definite article (“the”) and they capitalized the word “Son”.