You start with the premise that the "Dj" in Django sounds like the "J" in James or Jason or jangle or nearly every other English word with this pronunciation. Now, based on linguistic history and French pronunciation norms, you claim it is more appropriate to conclude that all of these other words have implied "D's" than to conclude that Django has a silent "D".
You might be right that the pronunciation of James with a phonetic /dʒ/ sound is a historical oddity, but it doesn't make your conclusions any more valid. If the J in James and the J in Japan and the J in jerk and the Dj in Django all sound like /dʒ/ the conclusion should be that the D is silent in English, not that the French are more correct than we are.