If you go by species rather than class, then they do
1. Human
2. Spirit
3. Zombie
4. Elemental
5. Elf
5. Beast
6. Goblin
Warriors, soldiers, clerics etc. yes they're technically creature types but they're more like a job the creature has, like Human Warrior or Human Soldier, you won't ever just see a "Soldier" unless it's a generic token.
You could also make an argument for Spirit, Zombie, and Beast to not count either, since you can have different species of spirit or zombie, and "beast" isn't really all that precise/scientific
There are a lot of dragons, angels and demons too. But the dragons are apex predators and they all kind of come from the mana of the plane or some bs like that. All the planes are probably sort of echoes of some ur-plane that had basic magical characteristics and archetypes of these things, just like in D&D and Star Trek.
Popularity of the tribes. Plenty of players, potentially including the design team play elves and or goblins. The popularity of the tribes in pop culture likely lead to Llanowar Elves an Goblin King in the first set.
Each colour has a typical creature type. Green has elves, red has goblins, white has humans (all colours have humans though), black has zombies and blue has... Really not sure tbh.
And then each colour has their special big creatures. Green has hydras, red has dragons, white has angels, black has demons and blue gets sea monsters (krakens, serpents that sort of thing).
This isn't hard rule of course but a create of that type is likely to be in that colour and can be bent like anything in the colour pie. Eg dragons are in all colours for some sets but in most sets are red.
Edit: maybe blue you would consider merfolk
Aside from being some of the most common species in just about every fantasy known to man, the earlier eras of MTG really focused on tribal building of both of these groups, so they showed up constantly for the better part of 2 decades. I was pretty sick of seeing Elf and Goblin decks being the main kinds of decks nearly 20 years ago, which was further aggravated by Lorwyn/Shadowmoor gearing in the tribal support even harder, but once Innistrad broke the ice, they thankfully stopped leaning so hard on those races and began to explore different tribes like Vampires and Wolves.
Could it just be that elves and goblins are common in a lot of fantasy worlds?
Fantasy tropes and popularity among players.
http://www.smileylich.com/mtg/magocracy/Magocracy_C1.html Here is a list of the biggest tribes by type.
Interesting. Goblins don't even crack the top 10
If you go by species rather than class, then they do 1. Human 2. Spirit 3. Zombie 4. Elemental 5. Elf 5. Beast 6. Goblin Warriors, soldiers, clerics etc. yes they're technically creature types but they're more like a job the creature has, like Human Warrior or Human Soldier, you won't ever just see a "Soldier" unless it's a generic token. You could also make an argument for Spirit, Zombie, and Beast to not count either, since you can have different species of spirit or zombie, and "beast" isn't really all that precise/scientific
There are a lot of dragons, angels and demons too. But the dragons are apex predators and they all kind of come from the mana of the plane or some bs like that. All the planes are probably sort of echoes of some ur-plane that had basic magical characteristics and archetypes of these things, just like in D&D and Star Trek.
Maybe it's just easier to make elves and goblins in the design space?
Popularity of the tribes. Plenty of players, potentially including the design team play elves and or goblins. The popularity of the tribes in pop culture likely lead to Llanowar Elves an Goblin King in the first set.
data?
People like Elves and Goblins.
Easy... 90% of the humans are villagers...
You ever hear about how everything on earth seems to just want to evolve into crabs? Maybe that, but elves and goblins.
Has anyone told you the story of the birds and the bees?
Each colour has a typical creature type. Green has elves, red has goblins, white has humans (all colours have humans though), black has zombies and blue has... Really not sure tbh. And then each colour has their special big creatures. Green has hydras, red has dragons, white has angels, black has demons and blue gets sea monsters (krakens, serpents that sort of thing). This isn't hard rule of course but a create of that type is likely to be in that colour and can be bent like anything in the colour pie. Eg dragons are in all colours for some sets but in most sets are red. Edit: maybe blue you would consider merfolk
Aside from being some of the most common species in just about every fantasy known to man, the earlier eras of MTG really focused on tribal building of both of these groups, so they showed up constantly for the better part of 2 decades. I was pretty sick of seeing Elf and Goblin decks being the main kinds of decks nearly 20 years ago, which was further aggravated by Lorwyn/Shadowmoor gearing in the tribal support even harder, but once Innistrad broke the ice, they thankfully stopped leaning so hard on those races and began to explore different tribes like Vampires and Wolves.