You're thinking about it wrong. Monsters evolve. Humans seem to just always learn Magic. Kumoko and the other spiders only get it from specific evolutions.
But everyone has Titles and can buy Skills.
- Shun is and his brother was "Hero." Julius probably didn't use it to the full extent, but Shun caused Fei to evolve just by being paired to her.
- Kumoko has Ruler of Pride and Sloth, which makes her stupid OP all alone, but she also has a ton more titles so far. "Kin Eater" gave her Hersey Magic, "Merciless" gave her more Heresy and resistance. "Thread User"... pretty obvious. "Foul Feeder" gave her poison and rot resistance...etc.
- Hugo had a stupid amount of skills compared to his classmates including Shun, had them ranked up higher, and had a Title or Skill boosting them further.
You really shouldn't judge anyone using Kumoko as a baseline. She's broken AF due to her extremely aggressive survival instincts and exhaustive level grinding. Humans without Hugo's drive take decades to get where she's gotten in year. Hopefully they'll show us Hugo's stats again now that he's presumably recovered a bunch so we can get a more even frame of reference.