[TtH Spoiler] Questions about Hood

Hello,

I am currently reading Toll the Hounds and I am past the part where a Dragon escapes the realm of Hood, and tells the high king about the war on death.

Now my question is since you can escape the realm of hood, it means you're still "alive" well not alive undead but you still exists.

Does that mean that before Hood became king of that real people would not die? they would become undead?

I mean what happened before Hood became a a god and got the realm? Is this explained further in the books cause it is confusing to me.

The way I understand it there was a time that Hood wasn't the god of the Death realm, so before that what happened?

Thank you.