Someone screwed-up Fate. I'm not saying any names like Voldemort or Malfoy or someone, but there is no way it should have happened like that. Harry DID NOT shake hands with Draco Malfoy. There I said…er…wrote it. And Ron definitely did NOT leave Harry to go and sit with his brothers and MOST assuredly accepted the apology Harry tried to give him afterwards and DIDN'T call him an evil git, or something.
Harry was sorted into Slytherin.
Harry took on Fluffy, a Devil's Snare, winged keys, a giant chess game, Snape's riddle and the mirror of Erised alone.
He slid through the schools plumbing down into the Chamber of Secrets to face Riddle and a Basilisk with only a fraud, a phoenix, and Gryffindor's sword (which wasn't a surprise). And Ginny Weasley, Ron's little sister, was Harry's first friend.
His wrongly accused Godfather kidnapped Harry, along with Ron and Hermione Granger, though Ron didn't talk or look at Harry the whole time. Ron took offense to Harry thanking him for helping to capture Pettigrew and getting Sirius exonerated (Sirius later became a Auror). Harry moved in with Sirius and Remus after Sirius's manor in the country became protected.
Harry was unwillingly entered in the Triwizard Tournament. Ginny defiantly was waiting for him at the bottom of the lake. And the Weasleys threatened Harry for his attention to Ginny. And Harry gave the twins his winnings, although he had to come up with an elaborate scheme that involved a Gringotts account and a Post-Office owl.
Harry left the castle on Thestrals alone with Ginny to go to the Ministry of Magic and fought off every major Death Eater alone. Dumbledore received a mortal wound and died at St. Mungo's three days later.
And Harry was transferred into Gryffindor at the insistence of Professor McGonagall.