Our distant hominid ancestors were far more human-like than we thought. A revision of the human origins timeline shows that many traits, like long limbs, a large brain, and the ability to craft tools, did not arise at the same time. Surprisingly, some traits appeared as long as 3 to 4 million years ago.
Given that the evidence now points to the different human "species" interbreeding and even living together, I'm not sure if we should even continue labelling them as different species.
That being said, there's still a lack of evidence on whether the interbreeding resulted in viable offspring, with some researcher's saying only human-neanderthal females were fertile so the debate will continue for awhile.
I personally think it's exciting that all the different human species might in fact be part of one big happy (incestuous) family.