Does anyone actually know the story for the original street fighter if so please tell me

All I know is Sagat was screwed over by Ryu in their match... Ryu got desperate to win and used a Metsu Shoryuken (Satsui No Hado version) and thats how Sagat got his scar.

If Ryu never resorted to the dark power Sagat would be the champion of Street Fighter I... And thats why he seeks revenge so much, although in his ending of SFIV he's no longer out for revenge.

I believe it was also the first time Ryu ever met Sagat. And technically, Ken was not a part of the World Warrior tournament, despite being able to play through the game as him if you're player 2. I think the story for Ken is that he was fighting in a U.S. Martial-Arts Competition of some sort, and then that's where he met Eliza.

As far as I know the two students of Gouken Ken and Ryu want to put their skills in shotokan arts(the gentler form of the assassins fist ansatsuken) to the test and that oppurtunity came in the form of the 1st world Warrior tournament in 1987. Sagat the reigning emperor of muay thai was believed to be the strongest fighter in the world (king of the hill) and waited for someone to challenge him. Ryu moved up through the ranks defeating the likes of Mike (the boxer from America) Joe (a kick boxer from America )Birdie( a thug from England) Eagle (a distinguished gentleman also from England )Geki (a ninja from Japan) Gen (an old assassin from China)  Retsu (Goukens long time friend) Adon (Sagats protege )and Sagat the pompous over confident champ who learned a lesson in humility at the hands of a desperate young upstart by the name of Ryu. Sagat had easily over powered Ryu and had him outmatched pinned down the hateful boy summoned all of his inner strength satsui no hado or the intent to kill and unleashed a feirce uppercut to  forever scarring Sagats's his chest. Ryu then went off to question his master about what went on and find more worthy opponents. Sagat joined a syndicate called Shadaloo and its leader M Bison promised the scarred warrior a shot at vengeance. Adon the pupil left his defeated master and went off to train and develop his own signature style he would later defeat Sagat in battle.