Is it wrong to judge how people behaved in the past based on today's morals?

It's easier to be able to pat yourself on the back for doing the right thing when that's what you're taught to do from the start and that's what society expects and you'll get plenty of support. It's harder to break away from doing the wrong thing or call people out on it when it's not regarded by the masses as the wrong thing. It takes more bravery to speak out against it when what you're saying isn't popular.