Those parentheses have to go.
The Ghost Embassy has just hired you, a human, to be their new ghost-human relations [expert? specialist? a word was dropped, and I don’t know what the writer intended] after the last one was…
If the writer insisted, for whatever odd reason, to keep the parentheses, the comma would need to go away instead.
The reason this sentence trails off with an ellipsis, by the way, is that it was created as a writing prompt, leaving the conclusion/explanation to whomever chose to use the prompt as the seed for a story. (That’s not your assignment, though.) I don’t like the use of the word human in this example. What are ghosts, if not the spirits/souls of deceased humans? Were I editing this for real, I’d recommend that the writer find a better word.