What was there before the Paleolithic and where really did life start for us humans, not like homo?
The partition in stone - bronze - iron is an early 19th century thing invented to explain to pupils the findings in north-western Europe. It has little modern day relevance.

Paleolithic (European ! Africa has a different chronology and the below is not generally applicable !) is a hand wavy container expression for anything from the first signs of human presence in Europe ~1.7my up to and including the last glacial maximum (lgm), and mostly refers to the life and strife of humans in the cold steppe. It encompasses different human species and subspecies, and in itself is divided into lower-, middel- (starting ~250,000) and upper paleolithic (~45,000) following stratigraphic expressions that what is above is regarded as being younger than what is below.

On a high level, lower paleolithic (again: Europe !) is generally connected with the presence of Homo habilis and erectus and ante-neandertals (i am being a "lumper" here), the middle paleolithic is the time of the Neandertals (Homo sapiens neandertalensis), and the upper paleolithic deals with the likes of us, Homo sapiens sapiens. All these units have further subdivisions based on tool technology and -industry. As an example, the upper paleolithic is further subdivided in (old to young) Aurignacian, Gravettian, Solutrean (around the lgm) and Magdalenian with their respective clearly distintctive stone and bone tool industries, and these have further local or regional expressions that deserve more detailed description.

With the onset of re-forestation human subsistance changes funtamentally. This is the time of the hunters and gatherers of the forests, the Mesolithic period in Europe, a relatively short period broadly taking place between ~9000 and 5500 BC. It lasts until and partly side by side with the incoming Neolitihic, the revolutionary (but not abrupt) change to farming, animal husbandry and settledness. The latter started over a few thousand years in Anatolia/Fertile Crescent/Levant between 11000 and 8000 BC (simplifying here for the sake of brevity).

Then it gets complicated. Metal (copper) has already been in use since in the Neolithic (see Chalcolithic), use of bronze starts in the middle east ~3200BC, and spreads north, arriving in central Europe around 2200BC. But it is not used everywhere (example: Egypt). Use of iron starts ~1200BC, arriving in central Europe ~800BC. 

Please keep in mind that there are huge regional or local differences with their respective own chronologies, because human subsistance and so the use of tools has never been uniform.

Regarding humans: We can speak of "humans" and the genus Homo with the onset of tool making ~2.6My ago, Oldovan stone tool technology in East Africa, though in these times there is not always and generally a link between a human species and a certain stone tool industry. The case of human speciation is complicated, and got even more so with the use (ancient) genetics as a tool for analysis. Though the latter is still a developin science, it looks like there have always been multiple species or subspecies around until recently. Today there is only one human species remaining on earth, and it is unclear how long they'll make it.

Pls. let me suggest to search the Biology departement here (or elsewhere) for an up-to-data primer on human species and subspecies.

Ok, questions ? :-)

Edit: since the original question has been clarified, i'd like to add something. First, there is no such thing as a single step that defines what an anatomically modern human (amh) really is. Evolution does not jump ! It is a gradual process of speciation, of adaptation to a niche. It may take place in a limited geographical region if individuals don't move far or over a large aerea, even over continetal limits if individuals or groups move in an out. As that's what humans did, things aren't exactly simple and in constant flow.

Find places of early amhs show that they developed, just like other humans before, in Afrcia, but rather distributed than in a single spot. Jebel Irhoud is up to now the oldest specimen with traits of amh, for the splitters among us in the field between h. heidelbergensis, rhodesiensis, neandertalensis, sapiens ...

But there is maybe another thing to your question, which is called "behavioural modernity". People using personal adornement, creating art objects like figurines, paintings of scenes from real life or more abstract symbols on cave walls, carving and painting mussels, etc. For a long time this was attributed to amh in Europe alone, starting with the arrival of the first groups of modern humans ~45,000 years ago. But recently, this was questioned, with the findings of traces from Neandertal find sites hinting to abstract thinking much earlier, 65,000BC in Gibraltar (Gorham Cave) and 115,000 in southern Spain. So, from a cultural point of view, there is no real "unique feature" in favour of amh any more, the differences are floating, not "carved in stone" (haha).

This is all in flow and debated. There'll surely be more news on all this soon (tm).