So, in part 3, we see that Old Joseph tells his grandson, Jotaro Kujo (our protagonist), that
stands were created by DIO's reawakening.
But in part 4, we see that
Koichi gets struck by a stand arrow, giving him the stand called Echoes.
These objects were created by
a meteorite that struck earth https://jojo.fandom.com/wiki/Bow_and_Arrow
stand arrows to appear, that were given to a young Diavolo
So did they both influence stands, or was it just one of them?