I think slurs are way more offensive than swear words.

Swear words are “offensive” arbitrarily. Some people don’t like “shit” because it is a more crude way to say “poop”. Most swearwords only became this way through classism. They were deemed offensive by the wealthy because they were initially used by the poor; using them was akin to associating yourself with the lesser classes.

Slurs are offensive by design. Their only purpose is to denigrate people based on their immutable personal characteristics (race, gender, sexual orientation, etc.)