I don’t know what “highest form of truth” means. Things are true in the world or they are not (or we have provisional evidence to say such-and-such is “true,” that is, the thing in question is true until additional evidence comes along — if it comes along — to knock out or modify what people previously believed). The word “highest” suggests degrees or levels of truth. I have no idea what these degrees or levels could be.

The Bible was written by flawed, mortal, and infallible men who were projecting meaning or purpose onto the cosmos in the absence of having any evidence to engage in such projections. You write: “Because God, in the Bible, claims Himself to be the ultimate standard of truth.” I would rewrite that as: “Because God, as imagined by the men who created this character, claims Himself to be the ultimate standard of truth.”

Yep, God is a compelling fictional character to many people. But not to me.