I find this claim strange. I am not aware of either RTB, or AIB claiming any particular race does not possess the image of God. This has been a problem in earlier times. But everyone today asserts that all living humans are children of God.
As to neanderthals, denisovans etc… how does claiming they have the image of God or that they don’t, have anything other than a academic value? These species don’t exist nowadays.
I firmly believe that the Bible teaches all human races posses the image of God. This is not an issue connected to race in anyway. Paul described this understanding as below-
Acts 17: [26 ] From one man he made every nation of humanity to live all over the earth, fixing the seasons of the year and the national boundaries within which they live,
27 so that they might look for God, somehow reach for him, and find him. Of course, he is never far from any one of us.
28 For we live, move, and exist because of him, as some of your own poets have said: ‘…Since we are his children, too.’
As far as Paul is concerned, every person from every nation (the Greek word is ethnos, related to ethnicity) is a child of God. God gives all people existence and acknowledges all as his children. He calls all nations to fellowship with him just as he did for Adam and Eve.