It’s hard for me to assume anything but Standard European Fantasy as the context for this stuff, given the obvious touchstones the game draws on. So some of this is going to deliberately push away from that. Since I don’t know enough about the playbooks, here’s some hot takes on all of them.
The Dwarf: sounds like a tank. “Greedy Dwarf” is boring to me. The other two angles they present are Artisan Dwarf and Earth Dwarf, so not breaking any new ground (ha ha, get it,… anyway). Theme song: Veteran of the Psychic Wars
The Elf:
The Halfling: actually sounds like a good candidate for low-level fairy folk. Feels plucky but with an undercurrent of tragedy or potential tragedy. We laugh to keep from crying. I’d go watch “Fiddler on the Roof” for inspiration. Theme song: L’chaim
The Harbinger: the multi-purpose Magic People. Grab something from TVTropes’ Witch Species page and go nuts. But it’s too vague for me to drill in on a specific interpretation just yet.
The Heir: feels like the default protagonist of the group, how do you get away from that? I feel like some limitation on the character, some unique hook or plot angle, would be needed. I’d love to do it something like The Princess Escort with this playbook.
The Orc: the illustration looked distressingly like blackface when I first looked, that’s awkward. I enjoy subversions of “orcs are bad” and I’d love to see an orc champion or hero, or a member of a race of orcs that uses war constructively - what about an orcish Rome?
The Squire: The Beacon.