Okay a few things, I have noticed this argument (mostly from ignorance) being used countless times against Evolution, both here and elsewhere. And it goes like this, evolution is just a theory, we are not sure and can never be sure. And hence, the whole thing is dismissed.
There are facts, that state something phenomenon occurring in nature, data if you will. And then there are theories to explain those facts, why does a said thing happen. A theory will never ever become a fact, no matter how much evidence you bring forth, no matter how many times you test its predictions. It will become a better theory, but it will remain that, a theory. In science a well tested theory is as good as it get, it is in-fact the real deal. Facts or laws are not interesting in comparison.
Gravity is a fact, things fall down. Newton's theory and now Einstein's General Relativity are attempts to understand why is that so. Einetien came and improved upon Newton's ideas, but while he was doing so, the apples suddenly didn't suspend themselves in mid air.
Also that didn't make Newton's ideas obsolete or wrong .They are so precise, that the rockets we use today, still use those results. You can reduce Einstein's field equations to Newton's, the latter are contained with into the framework of GR.
Similarly Evolution is both a theory and a fact. The fact of Evolution is not going to go anywhere, even if we develop a better understanding of how Evolution happened. Infact any new theory that tries to describe Evolution (always a possibility) will have most of the aspects of Natural selection in it, such is the evidence in support of it.
It is fact that organism change over time that is to say they evolve (phenotypes and genotypes of populations of organisms change over time) and it is still hapenning. It is fact there was only single cellular life existed on Earth 2 billion years ago which then evolved into multicellular life. There there we no Mammals or Birds 300 million years ago, these birds came from non-birds and us humans from creatures that weren't human.
Common decent occurs and is an observable fact; you, me and the chimps have a common ancestor. It is a fact that speciation can and does occur. A single species branch of into two distinct new ones over time (See Human chromosome 2, if are looking for evidence).
All this is directly based on genetics, fossils, embryology and is supported by geophysics, chemistry, and even astrophysics. Biological evolution is keystone is the advancements in medicine and health. To deny this is like denying the earth moves around the sun.
Now how did evolution occur? The explantation of the fact of evolution is a theory. Darwinian natural selection is one of many that try to describe evolution. But it is the one that has been tested countless times, gone through limitless criticism and has withstood them all. It is the most successful theory we have by far. To say it is wrong, it akin to saying General Relativity or Quantum Mechanics is wrong, while reaping there benefits each day.
So no, Adam and Eve were not the first Homo Sapiens, in-fact there wasn't a first Homo Sapien. There are no ifs and buts here, it is as established a scientific fact as any.
