Multiple people intuitively pointed out that the OP is actually quite wrong. The shocking fact, to me at least, is how far this goes: all of humanity share a single male ancestor [1] (and no, it was not the first man to ever live), and a single female ancestor [2], who likely lived thousands of years apart.
[1] https://en.wikipedia.org/wiki/Y-chromosomal_Adam [2] https://en.wikipedia.org/wiki/Mitochondrial_Eve
PS: see also references fromthe linked wikipedia pages