Social Justice Warlock
If you write it I'll try to do a zombie setting where the zombies are the good guys. "March of the Living Progressives" "Day of the Multiculturalism Advocates" "Liberal Nation"
I think one of the issues with the differences between various player race/species in fantasy games is that they are very similar to humans, and form monocultures. This encourages people to, consciously or subconsciously, try to *fit* them to groups you know. It's also a lot easier to, say, create a group of elves and make them nomads, so you do research into the mongols and pattern their customs after those people.
You're basically just creating a single cultural group of humans, except they aren't humans. This is why, say, making them less intelligent can come across so unfortunately. If your fantasy race is a bunch of giant spiders, then it's harder to map them to a human stereotype. It's still possible (people mentioned the insect hive-mind as a stand in for communism), but it may not take on as many racial connotations.
I favor distinct physical differences that lead naturally to differences in how they are played and presented. It's easier to build culture around the idea of "giant semi-communal spiders," because you can look at spiders and go,"What has to happen for them to form social units like humans."*
"How would they feed themselves? Would they have a sustainable food-source revolution like humans and agriculture? What do their shelters look like? Do they form towns? If so what are those like? How do they communicate?"
These can be spun into deeper philosophical or cultural differences. It also helps to back fill some history and cause some seemingly pointless schisms. Create a basic set, then say at some point in history they had a sharp disagreement about dietary needs or proper teaching or something. Split them into groups. Think about how those social units evolved.
Also don't forget that cultures merge and learn from each other.
Worldbuilding like this is kind of complicated and probably a bit exhausting, though, so I don't blame people who don't do it. It also might verge a bit on the sci-fi side of fiction for some people's comfort.
The benefit of this is that if done correctly, it can make it seem more natural when players interact with these different species. You recognize the way that the giant spiders construct low sprawling structures with many wide, short entrances at different heights. You get to enjoy their string-music art form that considers the construction of the instrument as key as the manipulation of it.
It also means you can have multicultural groups by blending these factors. Think about what has to change to include people with human shaped body plans instead of just being giant spiders. Humans need more upright entrances, less areas where it's assumed you can climb walls. They can't make their own silk, so it has to be provided. Etc, etc.
*You can replace "giant spiders" with anything. Big animals, humans but with different body-plans (centaurs or winged), humans but they're carnivores instead of omnivores, etc, etc. This makes it easy for the player to grasp how to play them.