It's more complex than that - You aren't wrong, but there's a lot more going on. Almost anything made by an employee as part of their job belongs to the company. If Amazon licences your work to make something based on it, that's one thing, but if you are a jobbing writer who gets assigned to develop a new series, Amazon will own everything. You get paid in your salary, not in royalties. And, frankly, a lot of creatives are quite happy with that arrangement (since it's so rare to make money at all).

And that's why it's... Odd. Because the "creator" is some dude who has already been paid; literally has received his salary. But the performance of his show does impact him, at least to some degree. Low ratings don't mean he gets paid less, but it means he's unlikely to earn more in future.