The only way someone's posture would be that straight is if they were standing at attention, a la soldier style. Was this your intention?
If you have a full length mirror, go stand in front of it casually. You'll see that you won't be standing completely straight, even without a slouch. Arms also don't usually fall straight down, unless - as mentioned above - they are standing at attention. It's a bit hard to illustrate this from the side, so perhaps you should start drawing from different angles. The two images we've seen from you so far are side views, and even under the best of circumstances their silhouettes will come off as a bit boring.
A very valid point, however you are almost totally correct, you see, as I previously mentioned "And yes I am aware that the pose is still a stiff pose, but I wanted to make it somewhat relevant to the first concept of Shane." I figured it would be easier to compare the two if they were rather similar. So one could say standing at attention was 'essentially' the goal. I will, for everyone, try a much different pose if you guys would be so kind as to permit me some time, I am swamped with school right now and may take a while. Thank you for your contribution! You guys are all so great!