Ugh...
1. Rain is from the ancient realm of Edenia. He hails as the child of Argus, Edenia's protector. It is currently unknown who his mother is, however Argus's shame of infidelity, caused him to exile Rain from his royal family. As a result, Rain was given to an unnamed, but key general, in the Edenian military. Rain is a demi-god, the son of a true god, and a human....
Seeing how taven and deagon were both alive way before edinea fell, it makes sense that so too was rain. Also it is known that Deagon was woken early and KILLED argus, thus making edenia lose its protector.
Which leads me to...
2. Yes a cameo means something in mortal kombat. When has it ever not? In every game throughout the entire series, there have been little cameos here and there and they have ALWAYS meant something.
3. Your last point is easy to shoot down because if you change one little thing in the past, you open up for a gigantic change in the future. Raiden was directing things based on his visions, and that changed everything.
and your wrong about the whole mileena thing. she had the same reason for being created here in both games. she was created as a backup in case kitana every turned on him.
Ermac... guess what? edenia and outworld have been merged a long time now... so its all the same thing.
Kabal could have left the clan because Kano was never returned to earthrealm after mk1 and stayed in outworld to give them weopons and was never shackled in the Colosseum.
Ok, you're about 2 responses too late...
Did you read any of the last posts on the last page? I assume not. When you do, I'll respond to the part about Argus being Rain's father (which is yet to be proven in the new timeline).
Anyways, how the hell am I wrong about Mileena when the reason you gave was the EXACT same thing I stated? It's actually you that is wrong. In the prime universe, Mileena was originally created to completely replace Kitana if she were to turn away from his influence, but the flaws in her design (her Tarkatan teeth) made him instead make her keep a close eye on Kitana and make sure she stays loyal to Kahn, all the while pretending to be her "sister". Shao Kahn was more fond of Kitana in the original timeline, in this one he is more fond of Mileena, his "true" daughter, and she was not created with the purpose of watching over his "sister" like in the original timeline. In the original, she also developed a deep hatred for her sister, but in MK9 she doesn't have this jealousy due to only being created during MK2.
Edenia and Outworld weren't merged when Shao Kahn killed all the Edenian warriors that would later become Ermac. His UMK3 bio stated that his souls were deceased Outworld souls, which implies that they were native to Outworld.
And about Kabal, correct me if I'm wrong, but his MK3 ending said that he was a Black Dragon member when he was severly injured by Kahn's extermination squads.
And a cameo does not always mean anything in MK games or any game. That's why it's called a cameo. Are you going to tell me Rain's cameo or Kintaro's cameo in Deception's conquest meant anything canonically?
Raiden only changed many of the events of MK1 onwards, solely because of his visions, which he obviously didn't receive until the start of the 10th MK tournament in Earthrealm. He alone never changed anything before then. NRS just redid some of the established things with this particular entry being a reboot.