There are main factors that allow human Wizards to be competitive with Elven mages, these are:
- Monofocus
- Risk-taking
- Arcane Marks
The Elven curriculum emphasises learning all eight Winds as a whole, splitting a student's attention eight ways. The Colleges's curriculum concentrates on learning only one Wind, meaning a Wizard can focus eight times their attention on studying their Wind than their Elven equivalent. That's an
800% efficiency increase in terms of progress in learning Wind magic vs time spend learning Wind magic. What a human student learns in ten years requires an Elven one study for 80 years to reach parity. A Magister that's been going around being a Wizard for a hundred years (not implausible given Wizard lifespans) would have as much skill manipulating a Wind as an Elven mage with eight centuries of experience learning all eight. Even for Elven lifespans 800 years is a very large amount of time. In practice this disparity in speed of skill progression is further enhanced by the other two factors, risk-taking and Arcane Marks.
The Elven paradigm is a conservative and safety-focused approach based on avoiding miscasts, when learning a spell a student learns all the ins and outs of the spell to fully understand the it before casting it to minimize the chance of anything going wrong. The Colleges meanwhile not only take a much less risk averse approach to their curriculum, they actively encourage a degree of risk-taking among their Wizards so they may be able to encourage greater things. When learning a new spell they do not require the student to fully comprehend the spell before casting, instead they follow a learn-by-doing approach, teaching the theory behind the spell and then having them try to cast it on their own and figure out how to do it properly on the fly. On one hand this means their is a significant chance of a miscast, on the other hand this means you can skip teaching large amounts of preparatory groundwork and theirs a chance that the students on the fly adaptations will result in a Mastery which is another advantage Elves can't have, and even if their is a miscast that miscast might result in an Arcane Mark which human Wizardry's third advantage over Elves. This risk-taking attitude also translates to a higher effective level of magical ability, not because being a risk-taker makes you better at casting spells but because it means you're willing to cast spells that you haven't 100% mastered because you're willing to eat the chance of a miscast in exchange for greater combat utility meaning you're effectively a more powerful Wizard than you should be on the battlefield and when that strategy does backfire and you do eat a miscast you again have the silver lining of the possibility of an Arcane Mark. Risk-taking attitudes also leads Wizards to do crazy things to make themselves more powerful like developing what are essentially artificial Arcane Marks in the form of Gilding or binding Apparitions directly to their souls to circumvent the normal limitations the thematics of a Wind impose on spell creation. Yes this results in a lot of Wizards dying while taking these risks but those that survive often go on to accomplish great things and the Colleges are of the view that quality is more important than quantity and the number of miracles both major and minor that Wizards accomplish on a regular basis seem to vindicate that view. Plus human Wizards are simply more expendable than Elf mages, it takes centuries to train up a replacement for a dead Elven Wizard compared to mere decades for a human one.
Finally there is the third factor, Arcane Marks. Arcane Marks not only grant an intuitive understanding of the relevant Wind making spellcasting easier they also make your soul actively better at channeling your wind. A human Wizard's magic score is nominally capped at 10, no matter how skilled they are, with Arcane Marks however that changes as their souls are no longer fully human, allowing them to cross that barrier and ascend to greater heights. The intuitive understanding of a Wind granted by Arcane Marks is what allowed things like Mathilde whipping up MAP on the spot or creating Rite of Way in a year and a half when Elves usually take decades, and if you're lucky enough to get the Mark of [Wind] Arcane Mark you can get a very significant boost in magical power. And all of that is an advantage that Elven mages can never possess.
That said it isn't all sunshine and rainbows for humans, while all of the above allows human Wizardry to be viable in the face of the Elven magic it still has a number of disadvantages compared to the Elven paradigm. First and most obviously a human Wizard is much less flexible than an Elven mage as they can only use one Wind, although this disadvantage can be mitigated by creative use Winds to generate effects that intrude into the conceptual territory that is Cardinally aligned with another Wind or by employing teams of Wizards of different Winds working together. Secondly humans are completely incapable of using High Magic, meaning that if you can't contrive a way to fit the desired effect of a spell into the thematic territory of any of the eight Winds you're SOL, although again this can be mitigated by using ritual magic which is not bound by the thematics of the eight Winds. Thirdly while the average Elven mage is still better at magic than the average human Wizard although the disparity isn't hopelessly large, for all the advantages human Wizards have Elves have their own advantages in the form multi-wind casting, longer lifespans allowing for more time spent learning magic even if that time is being divided eight ways, and being naturally better at manipulating magic. Fourthly while humans can invent spells much faster than elves this advantage is somewhat mitigated by the fact that they basically have to invent the spell twice, first to invent the spell initially and get it working in the first place, second to codify it into a form that any Wizard can cast, essentially porting the software of the spell from their own soul into a form that can run on everyone's souls by removing the hardware specific implementations reliant on quirks of your own soul's hardware that other people's souls wouldn't have. Fifthly not every Wizard can master the full curriculum of their College, either because they can't cast certain portions of their spellbook as is the case with Johann or because their magical abilities top out and they can't advance any further as is the case with Perpetuals, many Journeymen, and even some Magisters.