In Chinese, “Shen” can also refer to any false god; any idol. It must be marked specifically when used for the True God, which is usually done by leaving an extra space before the character for Shen. In Hong Kong and Taiwan, most editions of the Chinese Union Version, 1890 (the most widely used Chinese translation) uses ShangDi for the True God and Shen for false gods.
Same for the English word. We usually get around this by capitalization.
I'm not sure what your point is.
ShangDi was the ancient Chinese "Supreme Being" for thousands of years before Christianity. Very similar, in fact, to the position of Allah for Arabs prior to Islam. Most polytheistic religions have a "supreme god" that doesn't interfere in the slightest with their worshipping many others.
http://en.wikipedia.org/wiki/Shangdi