Tan. Have you ever stopped to think about this possibility: That Capitalism is a system which increases production based upon exploiting negative human qualities, such as greed and self interest. And it'sbecauseCapitalism exploits these qualities rather than suppress them, which previous systems used violence to do (For the lower classes), that we have greater production. And because we have greater production, there is less scarcity, and we are less prone to barbarity. Think about it, for a moment, in previous systems--every time greed/self interest wasnotsuppressedthrough the threat of violence, say, among the aristocracy, it ended up spiraling out of control. Capitalism doesn't attempt to suppress it, it attempts toharnessit, for all social classes (And no, it doesn't always work, but it works BETTER than anything previously--I could also write about how it works "better" for X class and how the elite exploit it, but this is a short, rough overview).
In other words, it's just as possible to say people are as shitty as ever, but the systems we have in place are better at spinning that shit into gold, as it is to say that people have gotten progressively more moral and ethical. If you look at any society that attempted to take these systems out, systems that direct greed and self interest into production, then you'll see it almost always devolves into another form of power collection that is overall far more reliant on violence for it's control and far less effective at spurring production (Even if innovation remains nominal).
The fact is, YOU are not smart enough to know whether your truth, or the above truth is correct. Neither am I. No one is. Some people have made some very educated guesses at it and that's why you see a lot of divergence in political-economic thought. But the fact remains, one system has proven to actually work, and increase most of the quality of life assessments we can measure--and that's Capitalism. You say there is a "next step", and I really hope there is, I really do, but there is very little evidence of it. The only thing we can point to, right now, is the success of more social elements in some Capitalist societies. Which leads me to believe there might be a next step, that maybe Marx was right, but his time scale was off by about 300 years.
I, personally, don't think humanity will make it to the next step until we achieve true post scarcity. And that's going to require fully mechanized labor, far more advanced resource synthesis techniques or some kind of singularity so we can have robot bodies. Until then? I do not, absolutely in no way, see a future built on the precepts that Marx thought existed below the greed/desire that Capitalism supposedly instills--I think that greed/desire is just there, and Capitalism simply utilizes it for production. And yeah, Capitalism might amplify them--but again, when we tried to suppress them? It didn't work out well (Historically or in modernity).
