Ok but this does not match what you said above. There is a long timeline here and interbreeding is a factor. Denisovans are certainly possibly just small H sapiens but H erectus did not exist 200 kya and Neandertals had a substantially different brain case. My guess is if they got language they got it via interbreeding with H sapiens.

The lack of evidence does create a lot of space for suggesting pretty much anything.