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I won't speak to the detailed of the Creationist point of view, but it's implicit in the Bible that humanity would have bottlenecked twice, once at Adam and Eve and again with Noah and his kids. So yeah, we'd all be related, and the first few generations after each bottleneck would have necessarily practiced some inbreeding to continue the species.
From an evolutionary viewpoint, we still necessarily have a a common ancestor somewhere back in the woodpile. No one special, but it's a mathematical certainty that unless two populations of humans evolved parallel to each other from completely separate lines of decent from there very beginning of life (which is both highly unlikely and not evidenced. Our DNA proves we share a common decent), there would be a single individual who is the most common recent ancestor for all of us. That individual wasn't the first human, just some random human who's descendants succeeded, where his/her cousins' or neighbors' descendants did not continue in an unbroken line down to today. When this individual lived is difficult to calculate, but recent estimates put him or her at only a few thousand years ago. Please note, that's just a date for the most recent human being who we can all trace in our family trees. That individual was by no means the first human, and he or she would have been one of millions alive at the time.
We also have a most common female ancestor in Mitchondrial Eve and a most common male ancestor in Y-Chromosome Adam. Mitochondrial Eve is the woman from whom the mitochondrial DNA (passed exclusively from mother to offspring) derives. She was no more special than our general most recent common ancestor, but the luck of the draw has it that we can all trace our maternal linages back to her. Genetic drift is fairly well understood, enough to act like a sort of molecular clock over large periods of time, so we can estimate based on our current array of mitochondrial DNA that Mitochondrial Eve must have lived about 140,000 years ago.
Y-Chromosome Adam is similar to Mitochondrial Eve in that he's the most common ancestor from whom all current Y chromosomes found in men today have descended. The molecular clock puts him at about 60,000-90,000 years ago. Again, he was no one special. He, Mitochondrial Eve, and our general most common recent ancestor did not know each other, and we don't know exactly who they were. We just know that logically, mathematically, they must have existed.
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