Old testament v. new testament

[fr0d0]

As far as I'm aware there is precious little to research at least historically, but happy to be proven wrong.

I'm suggesting you look thoroughly at the story you're relating. You'll then see the baselessness of assertions that God is in any way bad here.

I would state your brief analysis in stronger terms, ie a genocidal people looking to oust native tribes for their own ends,

That seems to hold true.

and inventing a god to justify there actions and hold a concensus amongst themselves despite their own savagery.

This is clearly invention.

But theism cannot duck this. Either there is truth in the claim that a god murdered the first born of Egypt or there isn't.

There isn't, because that's an inaccurate representation of the information.