"Jesus" is a version of "Joshua," and therefore extremely common among Jews at the relevant time period: as common as "Joshua" is today. "Mary," a verson of "Miriam," was also extremely common, as we observe reading the New Testament and trying to sort out all the different Marys, mother of this person, wife of that person, from this place or that place.
At least the names are gender-specific, though, so it's not like all the Taylors and Hunters and Dakotas today.
The Holy Spirit, or as we called it when I was young, the Holy Ghost, guarantees to me that Jesus was real, the Son of God Incarnate.
Scientists will never have a proof as solid as that, whether for or against that statement of belief.