Given $160K + $350K bonus for the first year, I assume this was an L6 role. In Amazon, an L6 engineer pretty much functions like a staff engineer and even a senior staff engineer. That is, they spend majority of their time sorting out priorities, convincing teams which direction to go with, and align all kinds of stakeholders. They are also responsible for the project management of those projects that span across multiple teams and sometimes multiple orgs.

So in a word, Amazon pays L6 engineers to sort out ambiguities and to shepherd teams. This may not be more complex than your work, mind you. It's just Amazon or companies large enough to have a tech ladder value this kind of role.