Honestly, this is a really accurate translation, which is why it has lasted in so many translations in English for so long. Nothing is added or taken away in translation (except the "O"). Perhaps a more understandable phrasing for this in modern English would be: "Listen up Israel, the LORD (who is) our God, is one God (not many)". This may have been an important assertion for multiple reasons:
- The name translated as "the LORD" was not a very familiar God and perhaps the name was not necessarily understood to be a single God and so it needed to be explained that this name referred to a single God.
- The Hebrew word translated as "our God" can be understood in Hebrew to mean "our gods". Perhaps this was also something that merited clarification and so became the first assertion of the Shema.
- The children of Israel were coming out of a polytheistic culture and encountering a number of other polytheistic cultures upon exiting Egypt. They were doing something totally foreign by worshipping only one God and so it was a point that needed clarified over and over in different ways.
Regarding the multiple interpretations of the word translated as "our God", this has to do with an ancient use of something referred to as "case endings" in Hebrew". In ancient Semitic languages such as Hebrew, there used to be different endings for words depending on their place in the sentence. Certain words like "God" kept one of their ancient forms even when the language simplified and so these words tend to look like "plural" words in Hebrew but are understood in context to be singular. For instance, in the first verse of the Bible, "In the beginning, God(s) (he) created…" the word is easily understood to be "God" and not "gods" because the action refers to one person doing the work: HE created (Who? One person, God).
