I understand your claim--genetics show humans didn't descend from a single mated pair ever.
Are you claiming that evolution produced multiple humans in one generation? Please explain that mechanism to me.
Changes between species happen over a course of many generations. There isn't a definite line that separates what is and what is not human. It is populations that change over time. And at no time was the population down to less than 1000.
Think of it like this: there was never a 'first French speaker'. But 2000 years ago, nobody spoke French. Now they do. The language changes gradually over time and was understandable to those who spoke it as a language at each stage.
So there was no 'multiple French speakers produced in one generation'.