I'll admit this is the first I've encountered the concept that "neanderthals and denisovians and so on" are not human. Maybe not biologically modern humans, but I'd certainly consider them fundamentally human.
https://www.nhm.ac.uk/discover/who-were-the-neanderthals.htm...
https://www.pbs.org/wgbh/nova/article/are-neanderthals-human...
The Wikipedia article [1] on humans makes the same point. It does acknowledge that some use the term human to refer to all members of the genus homo, but this is not the common usage.