One of the major points that the KJV-Only crowd often asserts is that the AV1611 was translated at a time when the English language had reached full (or significant) maturity with regards to spelling, grammar, syntax, and so forth. Such would therefore result in a translation that was timeless and there would be little to no need for any further update or revision. Of course, we understand this not to be the case and if you are going to use a King James Bible (1769 revision usually), you had better have an adequate undertanding of how the English language has evolved over the 400 years since the KJV was first published!
You raise valid points that suggest that English had not reached full maturity in 1611.
English at the time of the making of the KJV was in the period of Early Modern English and the period of the Great Vowel Shift so English had not reached its full maturity in 1611. David Crystal, who has been described as “the world’s greatest authority on the English language” wrote: “Modern English is obviously different in certain respects from the kind of Early Modern English represented in the King James Bible” (
Begat, p. 4).
David Crystal referred to “the pronunciation changes which took place during Early Modern English” (
Cambridge Encyclopedia of the English Language, p. 69). David Crystal added: “The changes were many and complex. The effects of the Great Vowel Shift were still slowly working their way through the sound system” (I
bid.). David Crystal noted: “
All the long vowels changed. That’s why it’s called a
Great Vowel Shift. And the spelling of all words with long vowels was affected, as a result” (
Spell It Out, p. 130). April Mahon wrote: “The whole long vowel system is radically reshaped between about 1450 and 1750 in what has come to be known as the Great Vowel Shift” (Mugglestone,
Oxford History of English, p. 184).
David Crystal noted: “The King James Bible looks backward in its grammar, and preserves many of the forms and constructions which were falling out of use elsewhere” (
Cambridge Encyclopedia, p. 65). David Crystal maintained that the KJV translators “often opted for older forms of the language, when modern alternatives were available” (
Ibid.). David Crystal wrote: “The
-eth [ending] was already dying out in Shakespeare’s day, and a century later wouldn’t be seen at all, other than in writers being deliberately archaic – or, as with
the taxman cometh, being jocular” (
Making Sense, p. 181). David Crystal wrote: “The third person singular of the present tense of verbs is always –(
e)
th. In other texts of the period, it is being replaced by -
s” (
Cambridge Encyclopedia, p 65). Concerning the KJV, David Crystal pointed out: “In particular, the modern use of
do with negatives and in questions is missing: we find
they knew him not instead of
they did not know him. By contrast, both old and new constructions are used in Shakespeare, and the
do construction became standard by about 1700” (
Ibid.).
April Mahon wrote: “As
thou slips away moreover, it takes along the matching verb ending – (
e)
st of forms such as
thou goest,
thou thinkest,
thou seest, which in turn contributes to that general reduction of overt inflectional morphology which, as we have seen, had been under way since the Old English period. In the same vein, the earlier – (
e)
th verbal marker for the third person singular present tense first comes to alternate with the originally northern –(
e)
s, and is gradually displaced by it” (Mugglestone,
Oxford History of English, p. 182). April Mahan wrote: “In syntax, the furthest-reaching development in early modern English involves the use of
do” (p. 183). In this same history of English, Terttu Nevalainen mentioned “two important processes of change in Tudor English: one that affected the third-person singular verbal ending (e.g.
he knoweth, which was gradually displaced by
he knows), and one that introduced the auxiliary
do into English (so that structures such as
they know not were gradually displaced by
they do not know)” (p. 221). Tertu Nevalainen wrote: “The rise of
do is a grammatical development which is, in histories of the language, particularly associated with Tudor English” (p. 244). Tertu Nevalainen referred to “the Tudor period from the late fifteenth to the early seventeenth century (1482-1603)” (p. 222). Terttu Nevalainen wrote: “Most speakers now associate –(
e )
th with archaic usage” (p. 226).