Well that's based of your personal belief which is irrelevant. Romans 9:24-26 mentions the Jews being called as well as the gentiles being called. Then it uses Hebrew scriptures to validate the calling of gentiles using Hosea the 1st chapter. Now if you read Hosea the 1st chapter it literally tells you that northern kingdom would be cut off and no longer God's people making them what? Gentiles. BUT they would again be called the son's of the living God which came to pass on Romans 9:24-26 thus we see Israelites being called gentiles. Accept it or not it's something you gotta deal with
Paul is speaking of being called to the gospel. He is not speaking of being called to the Sinai covenant. Paul is very, very consistent in preaching that Gentiles are not obligated to obey the Law. Like I've said, they are not Israel, so they do not have this covenant.
Again, you are not quoting any specific verses in Hosea 1 that mentions Gentile Israelites.
The northern tribes (at least those which did not flee to Judah as refugees) are lost to us. They intermarried. With very few exceptions (which have been found and restored by the state of Israel), they will never be found again until the Messiah returns.
It is therefore just foolishness for Gentiles such as black, Americans, British, or what have you, to claim that they are Israelites.
Those small groups which did turn out to be Israelites never gave up Torah observance, not ever, and never gave up their knowledge that they were Israelites.
I have a friend, last name of Ephramovich, whose family lived with Russian Gypsies. Now Gypsies commonly follow whatever religion is the religion of the culture in which they are trying to survive, so the Gypsy band in which his family lived was Russian Orthodox. YET his family was not. They lived by Torah alone, and did not eat unclean meats. Their family preserved the knowledge that they were Israelites. When his family was found by the state of Israel, they gladly became religious Jews and were fully united with the rest of b'nei Yisrael.
THAT's how it works. None of this silly let's tell Jews they aren't really Israel. It's all about reunification.