How can atheists call evolution a fact if a monkey turning into a human has never been observed? It's a theory and plausible explanation, but it's not a fact.
It's both a theory and a fact, the theory attempts to precisely explain the fact.
A monkey turning into a man is not evolution, that would be a miracle. As you so rightly demonstrate, miracles do not happen.
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Scientific theory is based on observation and experimentation, and is tested to a high standard. It's the nearest we can get to the truth about how nature and the universe work, and even that can eventually be shown to be wrong or require adjustment.
We and other primates are modern animals. We descended, branched off, from a common ancestor; and there will have been many such branchings of species - some of which will have survived and some will have become extinct - eventually resulting in humans, monkeys and other primates, and other classes. We're all still here because we've all survived so far - who knows whether we'll be able to adapt and continue to survive if the world changes beyond our ability to adapt, in a million years or less or more.
There might be various discoveries of possible lemur-like, or even shrew-like, ancestors. You might be better off asking about this in the Biology section. But we won't have come to definitive conclusions yet, if we ever will. But I have little doubt that our knowledge will increase over time, and we need to have the humility and strength to admit that we don't know everything, and maybe never will, rather than mask that by invoking a deity.
Evolution is a continuing process; species are continuing to disappear, evolve, survive or become extinct. There isn't any goal - there's no purpose or why, and it isn't chance either; it's natural selection.