Currently, the response from a CORS endpoint supplying data for amp-list must be a JSON object that contains an array property "items".
An unfortunate consequence of this is that a large number of public APIs are unusable, because they dont' return data wrapped in an items array. For example, GitHub's API returns directly an array of objects.
Here's a small amp-list sample trying to show a user's repos: https://jsbin.com/xekavu/edit?html,output
Proposal: add an attribute to amp-list allowing the developer to specify the name of the items property (default "items"):
<amp-list
layout=fixed-height
items=""
src="https://api.github.com/users/dandv/repos">