Dear L.,
I am not sure what difference it makes if some of the previous non-image of God hominids survived and mated with the new. Various things could have happened. When horses and donkeys mate, the resultant mules are infertile. In other cases the dominant genes can take over. I do not see any evidence that there are hominids around now who cannot engage in moral discussion and worship God as we do. Darwin himself discovered people who seemed to him animal like in South America, but on his second journey he found that they had come to faith and changed into fully moral human beings like us.
The important thing is that wherever the Bible has been translated and people have come to faith we are able to have total fellowship with such people of all races, and intermarriage causes no problems beyond ordinary incompatibility.
Bob.