Perhaps you are not aware of research over the past decade or so?
There is not anywhere near 100% agreement on this. There are some interesting outcomes of DNA research. Chimpanzees have 95% of human DNA but a Carrot has 80% of human DNA.
Well... Much depends on exactly how you measure things, but the usual numbers given put cows at 80%, fruit flies and chickens at 60%, and all forms of plant life below 50%.
Regardless, these numbers are a major piece of evidence supporting the hypothesis that all life on earth is at least remotely related and descended from distant common ancestors.