Thank you for the help! I hope you or somebody would be able to help confirm that this really was the location. It really does look very close and in that video, in some of the photos from above it looks like the water is very low, but still not completely surrounded by land. Pic related is the lowest water photo I found, and a PDF that says the depth is even less than one metre in some eastern parts of Homebush Bay:https://majorprojects.planningportal.nsw.gov.au/prweb/PRRestService/mp/01/getContent?AttachRef=MP10_0192%2120190807T061045.436%20GMT
I don't know if it could be the right location but still have doubts. The only completely landed ship I could find photos or information is smaller and surrounded by trees, so that isn't a match:https://www.bleakscenes.net/australia/homebush-bay/smaller-wrecks/
If it was Homebush Bay, the ship probably must have been SS Ayrfield. Then, the question is if the water level was extremely low on any of the possible years? Unfortunately my parents also don't remember which the exact years of full family trips were, to which places in which years. So, it could have been any year between 1998 to 2002. These were drought years so I'd expect some information about the complete exposure of a shipwreck to have been recorded if it happened, right? It is possible that very shallow water was present, however even pic related looks too high compared to my memory. Of course at the time I was a child so it's possible to have distorted memories...
To be absolutely certain that it was Homebush Bay, something about the water level in one of those years would be necessary. After all, if the water level was not at least as low as pic related on any year between 1998 to 2002, then despite matching very well, it couldn't have been. I have tried but couldn't find anything about that myself, or any photos from those years.