Species is a rather arbitrary line here. Humans split from Neanderthal ~500k-800k years ago but could still interbreed 40k years ago. We’re likely more closely related to our common ancestors at that point of divergence than Neanderthal suggesting given the opportunity modern humans could interbreed with our ancestors ~500k-1m years ago.
Of course that’s just genetic compatibility, there’s plenty of other ways to define species.
> Homo Neanderthalensis is not Homo sapiens [sapiens].
Not the same species, but still capable of occasionally producing viable offspring.
Thus the common ancestor as essentially a midpoint between each population would be more compatible genetically. It’s essentially a ring species through time rather than space. https://en.wikipedia.org/wiki/Ring_species
Of course that’s just genetic compatibility, there’s plenty of other ways to define species.