No everything that happened before still happened. All that didn’t happen is Pucci himself, that’s the whole point of his death at the end. He is no longer there to finish what Dio started, meaning Dio still does everything he does even the things that have to do with Made in Heaven but since his killed in Part 3 and the journal is destroyed, without Pucci being a thing anymore it means it all ends there. So part 4 and 5 still happens unchanged.
Now your opinion on Pucci is just your own feelings and there’s nothing I can say on that. Maybe you just don’t like that part of jojo and what comes after. Guess what you don’t have to keep reading or watching it if you don’t like it. Nothing about it doesn’t make sense, it’s not that hard to believe that Dio met some fag who became overly homo attracted to the point that he would want to finish what his boyfriend started. It’s just something you can’t seem to accept, and honestly that’s fair and your allowed to have those feelings. I just don’t think it’s something that doesn’t make sense in the world Araki has created. Like I mean every part other 3 is basically a “well this also happened while this stuff was going on”.
Edit: the stand ins in the initial recent are the people that would’ve replaced those characters if Pucci had completed his full cycle of Made in Heaven. If you die during the acceleration you are gone for ever. So when Made in Heaven was stopped before it completed all it did was erase Pucci instead. So those people that you see only existed if Made in Heaven completed but it didn’t so
The universe was restarted with everything happening as normal up to a few things like Dio never meeting Pucci and Dios plans ending at the end of part 3. It makes sense when you read it a thousand times and watch videos. Because I’ll agree that I don’t think Araki made it clear enough in the chapters themselves what happened.