[null and void]

There is no good reason from the text to assume that evening and morning spans something other than a 24 hour day.

From the text, no, no good reason. From the observable universe, plenty.

He spoke in human terms so we could understand it

It's an age appropriate response to the question "Where do babies come from?".

At some point "From the Hospital" is a sufficient and sufficiently accurate answer.

I don't see delving into the back story as necessarily a vain exercise.

[dartuser]

From the text, no, no good reason.

That's the whole point ... your reasons have nothing to do with any problem in the text. There are no Hebrew grammar, syntax, or translation issues in the text.

The reason why you have a problem with the text is that you seek to understanding the text based on something other than the text itself ... and that something else is what you are using to make the text say something other than what it says.