Why do Christians trust the Bible?

[Aractus]

1) I don't think the Israelites spoke hebrew while in Egypt. Furthermore Moses was raised in an Egyptian household. The earliest known hebrew writing dates from 1000 BC give or take a few years. (The gezer calendar)

Because they were never in Egypt. If they were in Egypt, and they were slaves, something would have been written down - regardless of whether or not they felt it fit to record the Exodus, a record of their stay in Egypt would exist.

2) Abraham wasn't native to Canaan. It's more likely he spoke and taught his children Sumerian or aramaic. Though we can be certain he could communicate with other Canaanites.

Abraham didn't write anything. The Bible doesn't claim that he wrote anything, so what he spoke is irrelevant.

4) when moses went for a total of 80 years out of Egypt he must have picked up certain words from the natives.

Moses is meant to have written down the Ten Commandments on stone tablets, twice. He's also meant to have done so on Mt. Sinai, however he and the ancient Israelites never actually went there!

6) when the hebrews settled in Canaan I doubt they'd speak Egyptian as fluently as their parents since they weren't born in Egypt. They'd probably have knowledge of local languages.

Right, even though Egyptians had heavily fortified strongholds like this one in Canaan at the time (there have also been two more that have been excavated and also date to the 15th - mid 12th centuries BC)? The entire Canaan region was controlled by Egypt through to the mid 12th century, and they still had a presence there after that (this is confirmed not just by their strongholds, but by hundreds or thousands of cuneiform tables of communication between Egypt and Canaan).

When the Bible was written (i.e. the Pentateuch), it was done so to tell the Israelites that they this grand history and that they were stronger than Egypt.

8) The first appearance of classical hebrew around 10th century BC fits perfectly with the Saul- David timeline

Except that no 10th century BC Hebrew has ever been discovered.