I think what I'll do here, is just focus more on the intent of the authors, because as you say father, much of the earlier reflections apply equally to the entire creed.
In this passage, there is an emphasis on "the only-begotten" or monogenes in Greek, or only-nature, only type, lone-nature etc, and is not particularly suggestive of His consubstantiality with us, but rather references the eternal Godhead that is a component (for lack of better terminology) in His nature, thereby expressing that He was not just a simple man as we are but that He was before all ages. Again, like Father said, it's hard not to jump into controversy mode because it is clear that there was specific reasoning for the emphasis of His Godhead at the time of the creed's composition.
So, from this statement, there is an indirect brotherhood portrayed between us and Christ, in that, the Father is also Christ's father, but as the passage also affirms, Christ is related to the Father in a way that we are not, as the only-begotten. We are sons and gods by adoption whereas Christ is Son and God by nature, and indeed the only one.
Substantial components that are left out of the creed are that of Christ's brotherhood with us; but this may have been because it was already assumed or well known at the time and did not warrant emphasis. Such is Christ being the firstborn of many brethren, and the first fruits, and Christ referring to those who are His mother and His brethren as those who hear the Word of God and do it.