If I'm correctly reading between the lines, are you implying that monotheism better describes what is going on in the OT rather than the divine plurality you find in the NT? Because that is not the case.
The term "Godhead" is an English variant of the word "godhood" and was first introduced by John Wycliffe (1330-1384 C.E.) in English Bible versions as
godhede. The word "Godhead" is a translation of three different Greek words,
theion (meaning "divinity, deity", # 2304 in Thayer's
Greek-English Lexicon of the New Testament) at Acts 17:29,
theiotēs (meaning "divinity, divine nature", # 2305 in Thayer's
Greek-English Lexicon of the New Testament) at Romans 1:20, and
theotēs (meaning "deity", # 2320 in Thayer's
Greek-English Lexicon of the New Testament) at Colossians 2:9.
To translate three different Greek words as one word and deviously incorrect at that in the
King James Bible, is no different than translating in the
King James Bible, the Hebrew word
she’ol´ with three different English words of "hell" (10 times), "grave" (31 times), and "pit" (3 times).
This is not unlike having three different names for one street on a map (with the real name hidden), so that when a person used it, he wound up lost. Likewise of those who read Bibles with "Godhead" in it, thereby misleading a person that the xxxxxxx is "real".
Hence, the need for an accurate Bible, one that renders Hebrew and Greek words and phrases with a high degree of precision, just as a map that can be counted on to provide exact information. Unfortunately, many Bibles follow the lead of the
King James Bible, or is otherwise biased, because the xxxxxxx, along with a host of other religious teachings that are not true, that has such a strangle hold on so many.