I've actually had the opposite impression. The list is so long... holidays, halos, resurrection, Greek, Egyptian, Budhist, Hindu, Pagan, and on and on and on. All preceding Christianity.
Individually I can accept some may be a stretch - but on the whole it seems very obvious Christ is not the original on many miracles and themes.
What you're describing is sometimes disparagingly referred to as the "many leaky buckets" strategy. The person trying to make the case knows that each individual argument is very weak, but he's hoping that he can make up for it in volume. Take Osiris for example. Yes, Osiris died, and he was later brought back to life. On a really,
really superficial level, that sounds kind of like the Gospel narrative. But if you actually take the time to google Osiris and read about his death and resurrection, you would see that it has almost nothing in common with the Jesus story, aside from the fact that they both involve somebody being raised from the dead.
Then you have to add in the fact that a lot of the "coincidences" people like to harp on in these threads are literally made up out of thin air. For example, Clif mentioned earlier that Osiris was ressurrected three days after his death. That "three days" part is just plainly wrong and is the invention of some guy on the internet that then gets reposted at half a dozen different crackpot sites.
The way threads like this go is these points get knocked down one after another, but then people come along and start rehashing mistakes that were refuted a couple of pages back.