Don't think of it too deeply, 活生生 just means alive or something looks alive, or something looks like having life force. like portrait is lifeless, but we use the phrase "活生生" to describe that it is living. And, your examples are perfect other than this example "我活生生的手". You can think in this way, you wouldn't describe your hands are living or alive in English, would you?. Of course you wouldn't right?. So this is why the example "我活生生的手" is not correct here. Here is another example: 他活生生的被折磨至死.