If Jesus was a completely fictional character, we have the apparent problem of his being written about as early as 70 AD (the gospel we know as Mark's gospel) and a whole following created . Which is more plausible, that there was a real person who was credited with extraordinary deeds, such as would be associated with someone sent by a god, by imaginative believers or that somebody invented a non-existent person who 'lived' only decades before they created him? It's bit of a stretch to think that, even 2,000 years ago, someone would place a fictional character to be passed off as real, in the equivalent of what,say, the 1930s are to us.
It is a common to find that real people are ascribed miraculous powers or deeds, be they witch doctors, Saint Joan of Arc, other saints in the Catholic church, or even kings (who decided that scrofula, 'the King's evil', could be cured by the touch of the monarch?)