The simple answer to the relevance of an original "human" pair, Eden - is this.
Present day human DNA includes about 3% Neanderthal and 5% Denisovan DNA in the modern European races.
These are two previous pre-modern human species.
It does not reduce to a simgle human pair - but to an evolved result of many millenia and many sub-species.
The DNA is simple, pure, digital sequence - it is without argument for or against.
It is what it is.
Tree of life has nothing to do with it.