That doesnt necessarily prove them to be "sacred"
These "eye-witness accounts" happened 70 + years before the gospels were written. For how long people lived then... and even today... im sure most, if not all, eye-witnesses had died off.
These "eye-witness accounts" could have been fabricated, or atleast some, in order to gain more followers, to make people believe, so that Christianity wouldnt be destroyed but would rather gain fellowship and grow to the ends of the Earth.
They could have been added later on, for we see the earliest texts found do not contain miracle stories.
Jesus could have existed. He could have also not existed. The stories could (keep in mind anything is possible, no matter how unlikely) be true, but they could also be fabricated, added on later, literary work, or etc.
The only thing that has named them sacred is the followers of the people who wrote them. Redundant. Biased. So there is acctually no *proof* that ANY "sacred" texts are sacred, including the Bible and its many, many translations.