No. Christ was the foundation of Christianity.
While there are many people who believe that the details and miracles of Jesus life were changed and embellish over decades, that is simply not true. the three earliest accounts of Jesus life appear to have been written less then 20 years after he lived. They are already being quoted in other writings by that time. And at east one of them predates the conversion and teachings of the apostle Paul. Paul, in his first letter to the Corinthians, includes over 20 phrases and two longer quotes from the gospel of Luke. This was written in 55 AD, or with 25 years of the crucifixion of Jesus.
There are also the writings of the Jewish Talmud, that includes writings by the actual Jewish leaders that conducted the trial of Jesus. They wrote that he was a teacher, healer and miracle worker. The write about his execution by the Romans, and about how his body disappeared from its tomb three days later with his follower claiming that he had raised from the dead. Why would people who opposed Jesus and his teachings have supported these events (that they lived through with him) if they were not true?
Sorry, but there was no time for a "myth" to grow up around Jesus. His miracles were already seen as established fact within 15 years of his lifetime.
Had the Jewish leaders wanted to kill the Christian faith, they could have just reminded the people - since it was only 15 years later - that Jesus never did any of those things. And they could have presented his body or pointed to his tomb. Instead they stated that the events were true and that his body had disappeared.
Keep in mind that Osiris was a deity that was worshipped for more than 1,000 years across many cultures that ruled in Egypt over that time. If you read through the myth about him, they vary all over the place.
The author of that list made a list of things that are well known about Jesus and then went through the hundreds of different myths about Osiris and picked one thing from here and one from there that were similar and then ignored the thousands of things that were not.
The "scholarship" behind that list is nonsense.