I'd like to make a gritty, realistic fantasy novel rooted in real history. I just prefer to read fantasy if it feels more grounded in historical fact. And that allows the book to be commentary on differences and similarities between a certain era and today, and I am fascinated by stories that do this well.

I'm a fan of A Song of Ice and Fire and want to write something similar. But the main reason I'm afraid is I want mine to be set during the Renaissance or a time similar to it because I'm fascinated by reading about the history of the time period. I like the "Age of Discovery" and the idea of that time as the beginnings of modernity and enlightenment.

But I don't want to ignore that the "Age of Discovery" was also an age of racism, colonialism, slavery, and exploitation.

This presents problems if you want to create a sympathetic protagonist people will root for. Bigotry was not just common, but global economics was based on it.

I don't want to do the Ever After/Mulan 2 thing where my hero or heroine wants/says things that are blatantly anachronistic just to appease sensitive people in the audience. My book would be about the unglamorous underbelly of history. Not the pretty picture in certain romance novels.

At the same time, I want the protagonist to be sympathetic. That's basically a requirement. They don't have to be a saint, but by today's standards, just the opinions of an average farmer would make most people wince.

Tl;DR: How do you strike a balance between what modern audiences want a hero or heroine to behave like vs. how realistically and accurately you want to show the time period?