[Everything in this post is casual ramble and if you'd like to revise/object/substantiate anything I've said I would love that. Also if you think there's a better fitted subreddit for this don't hesitate to tell me]
Last night, a friend gave me a rundown on cubism and what it did for the art world, arguing that its introduction was a static point in history and all art beyond it is a reiteration of the meta ideas that came with. Being very casually philosophical and artistic, I always like thinking about the application of meta-thought to art pieces and how it overtakes the original art. But before this level of expression was introduced, there was a more basic (and not less valid) level of expression, before all of this surrealism invaded what we consider art - simple paint to canvas for example, where a feeling or concept is conveyed through imitation (in traditional art forms) of real-life imagery.
First there's complete pragmatism, then there's traditional art, then contemporary art about art (about art about art about art...).
When was the first recorded step towards expression of any sort in history? Would you say there are further major developments that completely shape contemporary art beyond what was covered with the introduction of cubism? Are we destined to reiterate art about art about art about art etc forever?
It's tough to say which known work of art is "the earliest," since we are talking about objects that are 25,000 years old or more, and that predate written records. The dating of these objects comes primarily from radiocarbon dating and other methods that come to us from archaeological science. The people who created these objects are so far removed from our own experience of the world that it is hard to even know what was their concept of art, how they considered the objects they made, etc.
A few of the items that are sometimes advanced as the oldest works of art are the paintings in Chauvet Cave in France, the Löwenmensch or "Lion Man," a stone carving from Germany, and various venus figurines. The Venus of Willendorf is the one usually used in art history textbooks, though one or more others may be older by a thousand years or five. As I said, dating these things is somewhat less precise than it is for art made in the age of literacy.
I'd be interested to hear why your friend thinks that Cubism represents the conceptual end point of art. It's been something like a hundred years since Picasso and Braque first formulated Cubism, and I hardly think the art world has been conceptually static since then. If you can provide more specific sourcing or arguments, I would do my best to grapple with them. Cubism was undoubtedly very important.
As for your other questions, they aren't really appropriate for this subreddit. We are barred by rule from discussing events after 1996, and it wouldn't really be appropriate to speculate on the course of the future, anyway. You might try taking your musings to /r/arthistory, though to be perfectly honest I don't think much interesting discussion ever happens at that sub. Sorry.