quote: At one time, we were ape-like primates. We lived in the jungle, probably on trees. We became humans. Not overnight. But gradually, over millions of years. This is the accepted scientific theory about how human beings originated. According to this theory, there was no first human being. There was no Adam, nor Eve.
It is more accurate to say that the question of the "first human" is very fuzzy and not very important. That is, if we had a hard definition of human there would almost certainly be a unique individual who was the first to meet that definition, but it is populations that evolve and we would all be descended from a number of individuals in the population (and likely a very large proportion of that population).
quote: If you accept this to be true, how do you fit Mitochondrial Eve into the scenario?
Very easily. Mitochondrial Eve would be one of the descendants of the population which included the first human. And she would, herself be part of a larger population.
quote: Presently, ME is explained by saying the human population faced a bottleneck sometime in the past and that is why we have ME
Not really. Bottlenecking would only need to be invoked to explain the timing (which would affect the question of whether ME was human or not). It's a statistical inevitability that there would be some sort of ME.
quote: I am not saying that ME is the Bilical Eve. But, because we have someone like ME, I think it favours the theory that we are descendants of a single human being. Why then is the theory of bottlenecking more plausible than the theory that we descended from a single human being?
Because the bottlenecks we have evidence for aren't severe enough ! A single original pair would be a very severe bottleneck (and if you add in the Biblical Flood you get another severe one, too).
quote: Why is it we don't have the evidence for any of the other members of this population? I mean why is it that we do not have more markers that can be traced to someone who lived during ME's time?
Those are two very different questions. To deal with the second one we don't trace markers to individuals, just times. And if we could trace all of them to a common ancestor living at the same time that would be evidence FOR a single original pair.
quote: Yes. But is there any evidence to say it cannot be such a severe bottleneck?
My understanding is that the evidence is indeed against such a severe bottleneck (which IS evidence that there were other people living at the time of ME !). For comparison you could look at the problems of the cheetah which really did suffer a very severe bottleneck about 10,000 years ago.