No I think you are just taking this of the top of your head now.
There were those who saw Jesus as you have described https://en.wikipedia.org/wiki/Ebionites , there were those who followed the teachings of the apostles and the destination of the epistles tells us that the Christian communities were international. To say the messiah bit came later is you putting a one size history (which let's face it,in your hands is just customised Science ) fits all and could be construed as a bit of ultradarwinianism. Where everything that is has to have evolved.
Which was rather my point - although I tend not to talk about the specifics of the sects who didn't accept Jesus to be resurrected (for the reasons I will elaborate below), but to focus on the fact that very few of the people around at the time and place where this was supposed to have happened did accept it. By and large those people most likely to be early 'believers' (those around at the time and place) did not believe.
You don't strike me as having a very extensive grounding in history...GCSE?
Err yes, but as an academic I have training in the assessment of source material, which although I'm not an academic historian can readily be applied to a different field. In other word how to assess the quality and strength of a piece of source material. My son has just completed a history degree (achieved a very strong first and one of the highest marks in his dissertation) and I helped him to consider how to assess his sources.
But - and here is the nub - you mention the Ebonites - so let's look as the strength of the information on them from an academic historical perspective. Strong? Weak? Well we know nothing about them directly, everything we know comes from secondary sources, and those sources tend to be groups with a vested interest in not reporting on them objectively - hence the description of them as heretical. So we are relying on so-called early church fathers. So are they contemporary? Nope - the earliest of the early church fathers were around decades later.
But that's OK, we have what they wrote. Err, nope, in most cases we don't have anything they wrote, we have much later again (2-4thC) reports of what they wrote or centuries later copies that are likely to have been highly doctored and interpolated as they come from the era in history when the 'official' history of early christianity was being settled.
So from a historical perspective the sources we have for the Ebonites is very, very weak. As indeed it is for the whole historicity of Jesus, where information is exceptionally weak or totally non-existent. Which is why studies tend not to be consider academically to be 'history' but a different discipline all together 'bible studies', 'divinity' etc.