Please correct me if I'm wrong, but haven't we already identified at least FIVE unique "original" life forms/species that share no common genetic characteristics other than using the same DNA instruction processing system?
No matter, the burden of proof for a truly common ancestor is on Darwinists, and even if such an ancestor can be conclusively shown, it will only make Evolutionary Theory "remotely feasible", not even a shoe-in, in fact, not even the odds-on favorite (as the previously mentioned hurdles, math, etc. will still exist for it).