Evolution is an ongoing process. It goes on as we speak, exactly as it has for millennia. The same processes that can be observed today in the laboratory are the processes described by Darwin (although we have a lot more details after 150 years).
No one decided evolution shouldn't cover it's beginning, but Newton was able to describe the orbits of planets without "covering" their beginning. Using Newton's mechanics we can project their positions backwards in time. Planetarium shows do this all the time. Call it historical astronomy.
Not knowing how life started is not an impediment to understanding how it behaves now. Your argument is so ill-conceived that it is the equivalent of shitting on my carpet. You call yourself polite; I consider you a vandal.