The current consensus is that Homo Erectus left africa ~2million years ago. Homo Erectus were upright tool wielders, but were likely replaced by another wave of hominid from Africa - the ancestors to Neandertals and Denisovans - Homo Heidelbergensis around 500,000 years ago.
Ancient Eurasia had a variety of upright apes mostly originating from these. When Homo Sapien-Sapien, most probably both you and I's ancestors, left Africa (again in several waves between 40,000-70,000 years ago), they encountered, interbred with, and maybe warred with upright, almost human looking people, though the differences would be visible in the frame of the body and likely the face.
Neanderthals are thought to have split from Sapiens between 180K and 800K years ago.
It looks like the science is not settled on whether Denisovan separated from the common ancestors of Neanderthal and Sapiens or whether Denisovan are closer to Neanderthal.
Was it just an older form of human that left Africa and turned into Neanderthal/Denisovan once they got to their “final” localities?
When did this happen? What was the form that left Africa and eventually turned into Neanderthals?