First, it’s important to understand that the King James Version (KJV) is not simply a translation but God’s Word itself. In the Bible it’s told that God’s word will be preserved:
In Psalm 12 verses 6-7 it’s said:
The words of the Lord are pure words: as silver tried in a furnace of earth, purified seven times.
Thou shalt keep them, O Lord, thou shalt preserve them from this generation for ever.
Matthew 24:35 also says that…
Heaven and earth shall pass away, but my words shall not pass away.
And it was preserved. KJV is based on over 5,000 manuscripts which agree with each other. The translators didn’t use the 5% of available manuscripts that departed from the main doctrine of Christ and were therefore heretical and even widely disagreed between each other!