That's a statement (I gather) based on the Chang Paradox. If you go back 40 generations, assuming every living human has two parents (2), and each of them has two parents (4) and each of them has two parents (8), etc., by the time you get to 40 generations it requires a trillion different people (assuming your tree doesn't loop). 40 generations ago there we only 400 million people on earth . . . so there HAD to be LOTS of kings in your family. (Or the model has an inherent problem of oversimplification). In fact - looking at it purely statistically - EVERYONE alive in the year 800 is must then be related to you many times over . . . statistically. If you base genealogy only on Chang's statistical model.
Of course that is nonsense. And a classic example that figures don't lie . . . but liars figure.
But DNA does show that there were "fortunate" bloodlines that tie back and those currently alive can trace back a lineage of survivors. We are all the product of very resistant and dominate genes . . . or we would not be here. Last I knew it was still held that by looking at the mitochondrial DNA of humans we can be traced back to have had a single female ancestor some 200,000 years ago (very +/-). Her descendants are the ones that survived and spread.
Whether or not you consider here "Eve" is up to you.