No "We" here!
Daniel 2:36
36.
|1836| This {is}
|2493| the dream.
|6591| And its meaning
|0560| to declare, say, speak, tell
|6925| before, in presence of
|4430| the king.
Strong's Number: 560
Transliterated: 'amar
Phonetic: am-ar'
Text: (Aramaic) corresponding to 559: --command, declare, say, speak, tell.
Strong's Number: 559
Transliterated: 'amar
Phonetic: aw-mar'
Text: a primitive root; to say (used with great latitude): --answer, appoint, avouch, bid, boast self, call, certify, challenge, charge, + (at the, give) command(-ment), commune, consider, declare, demand, X desire, determine, X expressly, X indeed, X intend, name, X plainly, promise, publish, report, require, say, speak (against, of), X still, X suppose, talk, tell, term, X that is, X think, use [speech], utter, X verily, X yet.
Strong's Number: 6925
Transliterated: qodam
Phonetic: kod-awm'
Text: (Aramaic) or qdam (Aramaic) (Daniel 7:l3) {ked-awm'}; corresponding to 6924; before: --before, X from, X I (thought), X me, + of, X it pleased, presence.
Strong's Number: 4430
Transliterated: melek
Phonetic: meh'-lek
Text: (Aramaic) corresponding to 4428; a king: --king, royal.
Now it all boils down to this. You have no proof that the plural of majesty was never used before the Quran as your sources are contradicted by those of same equal elite status or higher among Christian and Jewish Scholars, thus rendering your proof as defective inorder to criticize the Quranic use of the Plural of Majesty
We have tons of proof. The entire Old and New Testament plus the Dead Sea Scrolls.