Those scriptures do not state they were black as in the modern-day concept of it. All it says is that they were tanned or darker than the other Jews, not that they were of a totally different race or ethnicity.
They were most likely dark skinned/tanned Jews, not Negroid/Sub-Saharan Africans.
Jesus has been reconstructed, he looked like this:
Those same hadiths describe Muhammad as a white dude, which I highly doubt he was. Those ancient people obviously exaggerated minor differences between themselves. Muhammad likely still looked like an Arab/Semite, same with Moses and Jesus.
Muhammad has been described numerous times as being whiter skinned than other Arabs.. Also, how is your dream a reliable source? It's just your brain playing tricks on you, not you actually seeing prophets.