Wednesday's titular main character was determined to keep a prophecy from coming true in season 1, and though she saved the day, the prediction was still correct. The first season of the hit Netflix series saw Wednesday Addams introduced to the world of outcasts, and she quickly learned that a prediction had been made that she would destroy Nevermore. Of course, parts of this prophecy were revealed to have been misunderstood. In the end, Wednesday solved the mystery and caught the bad guy. However, she still ultimately played a critical part in the villainous plot to destroy Nevermore Academy.
Wednesday season 1 revealed that Miss Thornhill was Laurel Gates and was using a Hyde (Tyler) and Wednesday to bring back Joseph Crackstone and lay waste to Nevermore Academy. However, long before this revelation, Wednesday was confronted by Rowan Laslow, whose mother had created a prophetic sketch that showed Wednesday destroying the school. This alarmed Wednesday, who became determined to keep the prophecy from coming true. Of course, it still did since it was the new student's presence at Nevermore that set the ball rolling.
The Prophecy Wasn’t Misunderstood - Wednesday Did Destroy Nevermore
When Rowan confronted Wednesday in Wednesday season 1, he was determined to kill her, believing that it was necessary to save Nevermore. What he didn't realize was that Wednesday would be the one to stop Joseph Crackstone and would therefore be Nevermore's savior. The Hyde killed him before he could understand, but the events of Wednesday prove that he had actually been correct, in a way. In the end, Crackstone would never have been resurrected if he had successfully killed Wednesday, and Nevermore would have been safe (for a time).
The ritual to bring back Crackstone required the blood of a descendent of Goody Addams, who had been the one to kill Jericho's founder all those years before. Therefore, by being at Nevermore Academy, Wednesday was filling in the final pieces of Miss Thorhill's plan. Crackstone was brought back to life, a good deal of Nevermore was destroyed, and the students all had to be sent home at the end of Wednesday season 1—and it was technically all because Wednesday had started at the school for outcasts.
What Would Have Happened If Rowan Killed Wednesday?
Since Wednesday was the most critical piece to Miss Thornhill's plan, she couldn't allow Rowan to kill her. This was why Tyler (as the Hyde) saved Wednesday's life, likely at Thornhill's orders. Of course, if the deceitful teacher hadn't thought to have Tyler keep an eye on Wednesday and Rowan had successfully eliminated what he saw as a threat against Nevermore, the events of Wednesday season 1 would have gone very differently. Thornhill wouldn't have had the final ingredient for her ritual and would have found it challenging to bring back her outcast-killing pilgrim-zombie.
Still, Wednesday wasn't the only descendent of Goody Addams, so this likely wouldn't have meant the end of Thorhill's plans. She had been working to take control of Tyler since before Wednesday (very luckily for her) appeared at Nevermore. Therefore, it's likely she had had a plan for getting ahold of an Addams even before Wednesday was expelled from her normie high school. Perhaps she would have found a way to get Gomez to Nevermore. Or, maybe she would have set he eyes on a far easier target, such as Pugsley.
Wednesday Season 1's Message Is About Trying To Stop The Future
Ultimately, it doesn't matter how much Rowan tried to prevent his mother's prophecy from coming true. A good deal of Wednesday season 1 was used to set up the fact that visions of the future are unpredictable and unreliable. At first, this seemed to indicate that one of Wednesday's visions would wind up being false, but this was never the case. Ultimately, every vision or prophecy had by one of the psychic outcasts in Wednesday came true—just not always in the way people expected.
Rowan's mother told her son that he must do everything he could to stop the girl she had drawn from destroying the school, but she didn't know that his futile efforts would result in his death. Then, Wednesday did her best to prevent this unknown woman's drawing from coming true, but it only further ensured that Crackstone was resurrected. Wednesday season 1 proved that the characters couldn't stop the future. Doing so only caused more woe for the students of Nevermore. Thankfully, everything still worked out in the end.