Ocean currents can't affect Earth's average temperature at the rate at which it is currently changing. Changing ocean circulation could melt ice at the poles and change albedo. But we have had significant warming long before our albedo was affected.
Yes.
Milankovitch is external. CO2 is a positive feedback mechanism which you've already chosen to reject. But CO2 doesn't drive the glacial-interglacial cycle. Milankovitch did.
CO2 will warm the planet (or cool it if removed) but it without humans or MASSIVE volcanism, it doesn't release itself into the atmosphere.
And remember the conversation is about what YOU listed as the causes of glacial-interglacial cycles, not every event in the planet's history.