Male Human - Probably someones first character who was new to the game or someone who wants to ‘play as themselves’. Probably boring irl. Probably from the burbs or a rural southern city/town.
Female Human - Achievement hunters. Can be either gender irl and usually really into all aspects of the game. Has exalted with everything and probably every battle pet there is.
Male Dwarves - One of the best friends you can possibly make in-game. The classic ‘bro’. He will give your lowbie alt runs and gold if you need it, and is generally a reliable and easy-going fellow. Will fly a cross the country to be the best man at your wedding.
Female Dwarves- Independent women who wish the world was a friendlier and nicer place and are bummed by humanities foul deeds in general. Sometimes get classified as an SJW.
Male Gnome- Stereotypical college kid even if not in college. Eats a lot of ramen noodles and probably really skinny irl. Talks the least in-game but does the best dps.
Male Pandaren - Stoned at all times. The true 420heads of the game, even more than trolls who often get put into that box. They always act ‘off’ and this is the reason why.
Male Tauren - Horde version of the male dwarf. One of the friendliest players you will meet. Will help you with whatever you need and is a genuine friend. Will be there to listen when you need it.
Male Undead- The most toxic player in WoW. Most likely player to s&^Tpost in trade chat or the forums. A teenage boy who wants to be scary and likes to gank Alliance as much as possible. Makes fun of anything possible when pugging, even your pet or your mog, let a lone your playing ability.
Female Undead - Usually nothing like the male counterpart. Typically an older female who is decent at the game and likes to keep a low profile.
Female Tauren - Older female who plays a resto druid and is married with grown or almost grown kids irl. Very kind and gentle, down to earth.
Female orc - Lf 3v3 2,400exp while riding around Orgrimmar on their crazy drake mount you’ve never seen before in your life with over 22,000 achievement points.
Edit:
Adding a few:
Worgen male: Monster movie/horror fan. Extremely into werewolves. Has no intention of ever activating their human form again for the rest of their time playing the game.
Female Worgen: Extremely independent woman, basically every single one will remind you of Fiona in the Plaguelands. Does their own thing and doesn’t care what others think usually.
Male Night Elf- Either a lighter version of the Pandaren or a player who wants to be ‘unique’ without being ‘different’. If playing anything other than a druid there is a 110% chance of them having a crazy mog with as much spikes, crazy lightning and glowing stuff as possible.
Goblin Male - 30s or 40s male who is confident and has a bit of success irl. Probably was really into stuff like beavis and butthead growing up. True 80s-90s kid. Shares races love of explosions and excitement.
Male Orc- Normal male who believes in traditional masculinity. Probably a bro but also likely to join the Forsaken player in making fun of you in a PuG if he thinks it’s funny.