My fanfiction theory is that there was a more original timeline which we never heard about. Skynet rises. Humanity loses. There is no resistance. Purely for sciences sake, Skynet invents time travel and sends back some meat (kyle Reese) it found in a cage it had forgotten to clean for quite some time to see if time travel works. Kyle in the past finds Sarah, I doubt he can talk after 20 years in a cage being a labrat to Skynet, so the only way they make a baby is if she's too drunk to notice he's a loser (happens all the time) or he rapes her.
Of course, that's if Kyle wa a field slave, he could have been a house slave?
Seemingly loyal to Skynet in the beginning, but then goes native in the past when he notices that no one is holding a whip any more. Of course once sent into the past they just had to find his corpse remains in the future, so they had to send him back terminal. Put a bomb inside him. Maybe a poison?
It's not just enough to make the baby, Kyle has to paint the correct narrative that "someone" raises John to start and lead the resistance, unless the second time through/around it's Kyle who leads/invents the resistance.
How does your timeline graph fit in with the Terminator/RoboCop comic book crossover?