Michelle
Your first bullet point shows the fallacy of making “unfairness” a new and powerful objection to GAE. The whole Bible revolves around grace - Israel is a clear case in point. Paul, 1800 years or so after Abraham’s call, points out to Gentile believers that before Jesus came (“just at the right time”) they were without God and without hope in the world. That’s not to say that God is unjust, but that his ways are not our ways.
But we needn’t stick to the Od Testament: the gospel universalised eternal life for all those who believe the gospel - and yet even now, 2000 years later, many have not heard the gospel, and there is no way that they could have done under God’s providence. The NT makes that difference radical - whoever is in Christ is a new creation in the Spirit… oh, pretty much same difference as that between Adam and “those outside the garden.”
The talk of unfairness by dragging “those outside the garden” into Adam’s sin seems a bit of a logical fallacy - the children of such unions are no more “those outside the garden” than I am still “non-Irish” because of my English ancestors, despite my Irish ones. To claim otherwise appears to me to play into that false racist narrative that the children of a mixed-race marriage are still “black,” as if they were not equally descended from their white parent.
Another thought that affects this arises from emphasising Adam’s entire heritage as the taint of sin. Though original sin is not essential to the GAE paradigm, it remains one way of accounting for the traditional Augustinian or Irenaean idea of ancestral sin (and those doctrines remain even without GAE). But more importantly, sin was only a side effect of the call of Adam, the central aim being to bring him into a living, new, eternal covenant relationship with God, and through him, to bring the whole race into such a covenant.
The whole drama of the Bible is the problem that the blessing brought a curse, and yet that God was able through Jesus to remove the curse and bring the blessing. If that’s not fair, then most of the Bible’s saving acts are not fair: Abraham was alone chosen to bless mankind: Moses was chosen and uniquely anointed to rescue Israel; David was “unfairly” appointed to head the Messianic royal dynasty; 12 apostles were chosen with special authority and responsibility to minister the gospel… it goes on and on. It’s called grace.