An implication is that any famous person from long enough ago, if they're not totally mythical and had any children at all, is your ancestor.
Biologists define the "identical ancestor point" to be the most recent time X in the past such that every person alive at time X is either an ancestor of everyone alive today, or of no-one alive today. Computer simulations suggest that the identical ancestor point is quite recent in geological terms, e.g., it's probably within the past few thousand years (it would be even more recent if we ignored remote places like Tanzania). See: Rohde et al (2004), "Modelling the recent common ancestry of all living humans", Nature. https://www.math.arizona.edu/~bhallmark/TMRCA/naturerohde.pd...
From the linked paper:
> In the case of Tasmania, which may have been completely isolated from mainland Australia between the flooding of the Bass Strait, 9,000–12,000 years ago, and the European colonization of the island, starting in 1803 (ref. 13), the IA date for all living humans must fall before the start of isolation. However, the MRCA date would be unaffected, because today there are no remaining native Tasmanians without some European or mainland Australian ancestry.
Oddly, portions of mainland Australia may have been as genetically isolated from each other as Tasmania, once particular environments were settled (ocean, river, desert, etc) they appear to have remained stable.
https://en.wikipedia.org/wiki/Truganini
day the Pintupi Nine entered the modern world https://www.bbc.com/news/magazine-30500591
Aboriginal mitogenomes reveal 50,000 years of regionalism in Australia https://www.nature.com/articles/nature21416