Everyone assumes that Uncle Tom was a character like Sam Jackson's Stephen from "Django Unchained" or Uncle Ruckus from "Boondocks". The character in the book is nothing like this. In fact, Uncle Tom is an admirable character. How this man's name became a slur is more complicated than it first appears.
The weird part about reading "Uncle Tom's Cabin" is that its advocacy literature, and most of us don't need much convincing that slavery is bad. But we need this context to understand that Uncle Tom was created by a white woman to appeal to a white audience because it's his tragedy that is supposed to persuade the reader. Uncle Tom didn't fashion himself to please some master like Calvin Candy, he was created whole-cloth as a device to awaken empathy of white audience. It's not his character, it's his raison d'être.