Not in the least. But an early and substantive Jesus movement lends significant credibility to the existence of a core Jerusalem cult. Provisionally assuming Jesus as cult leader is, in my opinion, far more reasonable that to posit a mid 1st century CE fabrication capable of producing such results.
On the face of it, I agree.
But put in context, and considering the actual contents of the beliefs and its pretty much indisputable "borrowing" of other, rivalling or older, ideas and religions, I think that quickly raises many many questions.
To the point that if this whole thing started with some single dude, it's pretty safe to say that that dude was very unlike the charachter described in the NT. So different that likely one might not even recognise him if contemporary evidence were found.
Another option is that he's a hodgepodge of various characters that over the years got blended together.
When either of these is the case, could we really answer the question "was there a historical jesus" with "yes"?
I personally doubt it.
That's kind of my stance.
IF I assume an actual historical individual formed the basis for these stories... I consider it extremely plausible that if we would find his contemporary and accurate biography tomorrow, we wouldn't recognise it as being the NT jesus at all.