That's completely missing the point of agency.

A slave lacks agency, despite being fully human and doing work. This is why almost every work of fiction involving slaves makes for terrible reading - because as readers, agency is the thing we demand from a story.

Or, for games that are fully railroaded - the problem is that the players lack agency, even though they are fully human and taking action. Games do try to come up with ways to make it feel like there is more agency than there really is (because The Dev Team Thinks of Everything is hard work), but even then - the most annoying part of the game is when you hit that wall.

Theoretically an AI could have agency (this is independent of AI being useful). But since I have yet to see any interesting AI, I am extremely skeptical of it happening before nuclear fusion becomes profitable.

Slaves do not lack agency. That's one of the reasons the Bible, specifically Exodus, is such a thrilling read.