Yes, in America racism towards blacks is the predominant problem within racism. Yet I don't think you do the cause any favors by claiming racism does not exist in other context or that racism is somehow only define as something white people do.
You could acknowledge that racism exists in other areas, but that right now racism against blacks is the central and most urgent topic.
It is harder to get supporters among non-blacks who also experience racism if you deny their experience.
Even by adding to this discussion I feel I am wasting effort better spent fighting actual racists. The left in general engage in far too much infighting, on this topic while the real racists are eating their popcorn and laughing at us.
A large united front would be more effective than lots of marginally different groups engaging in infighting about what often seems equivalent to different religious denominations bickering about the exact meaning of scripture.