I think that it is morally wrong to discriminate against people for things that they can't change. Believing that someone of a different race can't possibly be intelligent is a moral wrong.

The second statement here doesn't follow from the first. If intelligence is something that a person can't change, then it follows that it's morally wrong to discriminate against someone for being unintelligent. It doesn't follow that it is morally wrong to believe that one factor a person cannot change (their race) can determine other factors that they cannot change, such as their intelligence.

Whether there are actually average inherent genetic differences in intelligence between races is still a matter of some debate (although the issue is so politically charged that it's hard to get any effective unbiased research done, and attempting to do so can be dangerous for one's reputation.) It's certainly unlikely that any race exists that has negligible odds of any particular individual reaching an arbitrarily defined cutoff point for "intelligent" compared to other races, but this is an empirical matter which is to be determined on the basis of evidence, and moral considerations have no bearing on whether or not it's true.