[vessenes]

Well, we know that they could communicate (or be attractive enough) to interbreed with Homo sapiens — presumably they weren’t the genetically stronger species because their DNA is generally 1-3% represented in ours.

We don’t know, as you note. But the genetic evidence combined with tool use and their large Supra-orbital indices (fairly big brains, if shaped differently than ours) all would make that the preferred prior I’d say.

[pfdietz]

It's not clear how much interbreeding there was. It doesn't take many introgression events over the millennia to show up in the genetic record. And, to put it delicately, it's not clear any communication was involved in these events.