I think a fossilized hominid might have worse than average chance of having no living descendants too: To be fossilized they have to undergo a fossilization event, which is probably correlated with disaster: and given that ancient human did not stray far from their genetic siblings (and progeny) this probably indicates a high chance of that disaster affecting their progeny. I certainly wouldn't rely on it.

Nevertheless, given my cultural heuristic for what counts as most important, it would probably be father (in terms of how much various cultures put a value on either the father or the mother), or most recognized powerful ancestor (Salazar Slytherin in this case).