There is a distinct problem with your question, and that is that ‘son of God’, even referring to YHWH, is not a unique title in the Hebrew Scriptures in the same way that it becomes a unique title for Christian Theology.

When moderns hear ‘Son of God’ referring to Jesus, our default assumption is heavily influenced by some kind of knowledge of Christian Trinitarianism, in which ‘Son’ indicates the relationship between these two persons, God the Father and God the Son. Even people who don’t understand much Trinitarian theology tend to understand ‘Son’ in this ontological sense.

But neither the Graeco-Roman context of the New Testament, nor the Old Testament context, bear this meaning. In the case of the former, the G-R background is likely to understand ‘Son of God’ to mean what it does for pagan deities – a divine like figure. But in the Old Testament, ‘Son of God’ is functioning as a title for a representative of God, primarily the King of Israel. This is almost certainly the sense of ‘Son’ in Psalm 2 for instance. Which means that ‘Son of God’ language in the New Testament is bound up in an interpretive web with concepts of the Davidic Messiah, for which there certainly were other people claiming to be such a figure.

This doesn’t answer your question, but it should broaden it to a set of other questions:

1. What exactly does Jesus claim for himself in the documents we have?

2. To what extent are those claims unique, and to what extent are they the first claims of those sort?

3. What would Jesus’ contemporaries have understood by these kinds of claims?