Pretty Stupid Question (Prototype Amazon Pack)

Yes

yes you are stupid because Amazon clearly states 2 options where one says "STEAM DRM"

There's two editions, mixed DRM and Steam DRM. Make sure you select Steam DRM and you'll get keys.

If you ever want to confirm if an Amazon game is Steam DRM, use ctrl+F and search for "Steam". You should see a "Steam account required" somewhere.
In the case of Bundles, open the exact link displayed for that bundle. It is possible the bundled version will NOT be Steam, even if a Steam version exists.

But yeah, in the case of Prototype bundle, Its steam.