In Mecca of the 7th century, there was no complete Arabic translation of the Bible. The Prophet ﷺ was known to be unlettered, and his people, who opposed him, accused him of getting help from a man, and the Quran answers that the one they point to speaks a foreign language, while this is clear Arabic.
The Quran does not claim to be a copy: it states it confirms what is true in the earlier scriptures and is a criterion over them. It has stories that are not found in the Bible, such as the people of 'Ad and Thamud, and it differs from the Bible on the story of Abraham's building of the Kaaba, the nature of Jesus and others. The similarity is explained, in Islam, by one source: the same God.