Are there even left-handed main characters left? The most famous one that most people know, Link, is slowly becoming right-handed and I’m having a hard time remembering any other main characters who are actually left handed.
Some of the weapon types in Monster Hunter (Sword & Shield, Lance) have the hunter be left-handed

You know, I played a lot of lance and never realised that. I guess it’s because it’s right trigger to block?

I guess canonically that probably means hunters are ambidextrous.

I thought I read somewhere that it was mainly to stop weapon models clipping through armor in the first game, and the animations just stuck around

This is actually for lore reasons! Canonically hunters that we play as are right handed; the Hunter’s Guild believes that defense should be a hunter’s priority, and so they mandate that the dominant hand should be used for shields (where applicable). Presumably a left handed hunter would use their shield in their left hand.

There’s similarly lore reasons for why we have parties of only up to four hunters. One of the earliest hunter’s fiancée insisted on coming along for a hunt, resulting in a party with 5 hunters. During the hunt she was killed, and the Guild took this as a sign that a fifth hunter is sure to bring misfortune to the party, and so that tradition has stuck around out of a combination of Guild regulation, superstition, and to honor the fiancée who was killed.