Thanks to /u/voyeur324 for finding the earlier answer I provided. I’m always left a little puzzled by the term “cowboy” because media often uses it to mean, simply, a man in the West, but in the West, it refers to a ranch hand, a very specific occupation, and someone who was employed rather than even an owner of a ranch. It was an occupation that very few pursued compared to the West overall. There were African American ranch hands – “cowboys.” There were also African Americans employed at many other occupations.
I have not seen”1883” so I have no idea of the circumstance, but it is important to remember the example of James “Jim” Beckwourth (1898-1866) who was an African American frontiersman of the American West. Beckwourth Pass, which he discovered across the Sierra retains his name. He was an intrepid explorer and serves as an example (and a reminder) that African Americans were a presence in the West. Beckwourth could have easily slipped into the role of guiding a wagon train of settlers.
Start with the answers by /u/itsallfolklore I found for How prevalent were African American cowboys in the American West? but other redditors may be able to help you with your specific question.