English has a lot of words for ruler, and the list you've produced is not much longer than the list for D or any other common word-initial sound: duke, dean, dynast, duchess, dame, dronning, etc. You've also stacked the deck a little by including Caesar, which does not have a hard c sound in English, along with Khan, which does in English but not in the Turkic source. You've also included kralj, which is hardly a common word in English. Overall, I would surmise that this is nothing more than a coincidence.

Slavic kralj comes from Charlemagne's personal name (non-Slavic words with ar often changed to ra in early Slavic), so it's not really related to the others.