If your conclusion is that we don't know how to do value alignment, I and I think most alignment thinkers would agree with you. If the conclusion is that AGI is useless, I don't think it is at all. There are a lot of other goals you could give it beyond directly doing what humanity as a whole wants in any sense. Some are taking instructions from some (hopefully trustworthy) humans, and another is following some elaborate set of rules to give humans more freedoms and opportunities to go on deciding what they want as history unfolds.

I agree that the values future humans would adopt can only be reached through a process of societal progression. People have expressed this idea by saying that human values are path-dependent.

So, if our goal were simply to observe the values that emerge naturally from human efforts alone, an AGI would indeed be nothing more than a paperweight. However, the values humanity develops with the assistance of an AGI aren’t necessarily worse—if anything, I’d suspect they’d be better.

The world as it stands is highly competitive and often harsh. If we had external help that allowed us to focus more on what we truly want—like eliminating premature death from cancer or accidents, or accelerating technological progress for creative and meaningful projects—we’d arrive at a very different future. But I don’t think that future would be worse; in fact, I suspect it would be significantly better. It would be less shaped by competition, including warfare, and less constrained by the tragedy of involuntary death.

An AGI that simply fulfills human desires without making rigid commitments about the long-term future seems like it would be a net positive—potentially a massive one.

I think the paradox you mention is generally accepted to be an unsolved problem with value alignment - we don't know how to ask for what we will want, since what we will want could be a bunch of different things depending on the path, and we don't know what path to what values and what world would in any sense be best.

This is commonly listed as one of the big difficulties with alignment. I think it only sort of is. I think we really want the future to remain in human hands for at least some time. The concept of a "long reflection" is one term people use to describe this.

In the meantime, you either have an AGI whose goal is to facilitate that long reflection, according to some criteria, or you have an AGI that takes instructions from some human(s) you trust.

This is one reason I think Instruction-following AGI is easier and more likely than value aligned AGI. The reasoning there is pretty different from the conceptual difficulties with value alignment you mention here; it's just easier to specify "do what this person meant by what he tells you" than what we mean by human values - and you get to change your mind by instructing it to shut down. Even if that worked we'd have to worry: If we solve alignment, do we die anyway? because having a bunch of different humans in charge of a bunch of different AGIs could produce severe conflicts. But that whole logic is separable from the initial puzzle you posed.

Aligned with current (majority) human values, meaning any social or scientific human progress would be stifled by the AI and humanity would be doomed to stagnate.

Only true when current values are taked naively, because future progress is a part of current human values (otherwise we would not be all agreeing with you that preventing it would be a bad outcome). It is hard to coherently generalize and extrapolate the human values, so that future progress is included in that, but not necessarily impossible.