Somalis are 60% Proto nilotic. Nothing to do with the Niger Congo peoples of west/central/south & south-east Africa.
Somalis have never associated with a foriegn peoples, let alone a Christian peoples. We are an isolationist race who likes to keep to themselves and have a strong "us vs them" attitude to the world.
My great grandfather probably doesn't even know what a black person looked like, he was too busy on chilling on the red sea coast across from yemen and beefing afars to care about these people.
All Somalis aside from those living in the west, identify as somali & their clan only. We do not care about oromo and Afar in Ethiopia who are near identical to us, why would we care about Nigerians? No one in somaliweyn gives a damn about the "black race" they are irrelevant. Same thing with the "white race" who are also irrelevant in somali society. Heck Arabs and Indians got more clout in the mouths of people walking Mogadishu. We don't constantly talk about colonialism or white people like other african countries nor do we talk about black people. These two groups simply don't have any importance to the average somali.
In the diaspora it's different, we live in their gaalo nations. But still, somali don't easily give up their identity and will still see a black man as a foriengier. Because they are. All people who are not Somalis are Shisheeye. Black people look different & many Christian. They are as foriegn to the Somali as an Indian.
So the reason we don't identity with "black people" is because they are Shisheeye, foriengiers just like any other people. We have no history with them, they are genetically unrelated to us, why would we claim to be the same people as them? It's a lie and no proper Somali would beg it to a Shisheeye. We are a arrogant people who value lineage, not random colonial era concepts like the black or white "race".
The ones we live among in the west are Christians which is the religion somalis have fought against for a thousand years thanks to our historic rivalry with the highlanders.