Let’s suppose that we are alone. Now take our tiny insignificant planet out of the equation and suddenly there is no intelligent life in the universe AT ALL.
You would have to ask – what even IS the universe with no life form capable of observing it? I think I’m having a quantum meltdown just thinking about it.
On a more practical scientific note – is gravity an assumed feature of the goldilocks zone? I never see it mentioned. Always with the liquid water and breathable atmosphere, but I’d reckon sticking to the surface of the planet with just the right amount of force to enable free motion would be quite important. Or at least important for intelligent life that resembled us in any way.