Colonialists certainly did view cultures on a hierarchical ladder with western culture at the top. This was absolutely wrong. But I think we make a mistake if we blame Conrad and not the society that made his way of thinking the default.

In addition. I don't think that racism and colonialism exist in the same way today. If anything, we've had such a strong negative reaction to Colonialism that we've got too far in the opposite direction. Our obsession with inclusivism and relativism prevents us from making any sort of judgement at all when it comes to practices of other cultures.