What were Jesus and early Christians like?

[TimOneill]

He suggested to me the idea that all four gospels might have been working off an earlier narrative.

Then what your brother suggested doesn't fit the evidence. It indicates several separate and distinct lines of source, not just one. I tend to find careful reading of peer reviewed scholarship works better than listening to some dude who happens to be your brother.

But unless there is something substantial discovered, it seems to me like the speculations about when tales of Jesus originated in either oral or written form can go on and on, ..

Mere "speculations" are things that are simply possible, but which have no evidential support. Critical scholars work from things which are possible and which have the most evidential support and require the least suppositions. Occam's Razor. See the difference?

and it makes little sense if we assume that Jesus really was crucified sometime around 30-33 C.E., that immediately these elaborate stories began circulating...or perhaps that was a common feature of recently deceased Jewish wisdom teachers whom some small sect revered?

What?

Why could not Matthew and Luke had access to Mark and Q and wrote their narratives primarily based off those, with their own agendas and anecdotes marking the rest of the differences between them?

That's pretty much what every critical scholar on the planet thinks happened. So ... what?

To unite different factions of Jewish and Gentile Christians who had different expectations about the Messiah's birthplace and because Mark's Gospel was already considered authoritative to a substantial audience?

Ummm ... what? You need to come up with a reason we should think gMark's tradition that Jesus came from a village called Nazareth was wrong in the first place. Start there and see how far you get before Occam's Razor cuts your throat.

Over to you.

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You're argueing with a point I admitted I just made up

I'm noting it makes zero sense. Rationalists work with what makes sense.