Shahar also means a well known situation. Shahar (mashhoor is also derived from this word). Shahar ramadan means a well known situation which is intense (ramadan also means intense heat or sharpening of the sword). So the Quran is talking about an intense situation not the month of Ramadan. The hijra calendar was not invented until after the reported death of the prophet and then a month was named Ramadan, probably because it fell during hot summer.
the same verse should be translated as:
For this intense situation the Quran was revealed (so we take guidance from the Quran to correct the situation) and Soum (meaning stop and refrain from doing whatever is causing such situation......and so on.
But the main thing that we forget is that the Quran tells us that soum is something that will makes us righteous. Someone please tell me how going hungry and thirsty will do that?