Apparently the AV translators believed in the antiquity of the LXX. In their preface to the AV 1611, they wrote:

Quote:
While God would be known only in Jacob, and have his Name great in Israel, and in none other place, while the dew lay on Gideon's fleece only, and all the earth besides was dry; [See S.August.lib.12. contra Faust.c.32.] then for one and the same people, which spake all of them the language of Canaan, that is, Hebrew, one and the same original in Hebrew was sufficient.

But when the fullness of time drew near, that the Sun of righteousness, the Son of God, should come into the world, whom God ordained to be a reconciliation through faith in his blood, not of the Jew only, but also of the Greek, yea, of all them that were scattered abroad; then, lo, it pleased the Lord to stir up the spirit of a Greek prince (Greek for descent and language), even of Ptolomy Philadelph, King of Egypt, to procure the translating of the Book of God out of Hebrew into Greek.

This is the translation of the Seventy interpreters, commonly so called, which prepared the way for our Saviour among the Gentiles by written preaching, as Saint John Baptist did among the Jews by vocal.

For the Grecians, being desirous of learning, were not wont to suffer books of worth to lie moulding in kings' libraries, but had many of their servants, ready scribes, to copy them out, and so they were dispersed and made common.

Again, the Greek tongue was well known and made familiar to most inhabitants in Asia, by reason of the conquest that there the Grecians had made, as also by the colonies, which thither they had sent.

For the same causes also it was well understood in many places of Europe, yea, and of Africa too.

Therefore the word of God being set forth in Greek, becometh hereby like a candle set upon a candlestick, which giveth light to all that are in the house, or like a proclamation sounded forth in the market-place, which most men presently take knowledge of; and therefore that language was fittest to contain the Scriptures, both for the first preachers of the Gospel to appeal unto for witness, and for the learners also of those times to make search and trial by.



If you trust the text Bible version made by those men, why cannot you trust the other items they placed between its covers?