The god of the weave was a human and openly favors them. Also she has 7 human daughters who have had the last 700 years to pass on their genes. Not to mention all the borderline godlike mages that we know for a fact have been passing their genes, like Elminster.
And not to mention the drow example again.
There are parts of the lore that are unexplored and intriguing. I've always wondered what kind of kind of relationship Corellon and Mystra have. Corellon is the elven god of Magic in other settings but he seems to accept Mystra's rulership in all domains except elven high magic. There could be some tension in that relationship.
There are also some parts of the lore that explain why Mystra favors humans.
Spoiler for length
When WotC was first trying to figure out how to respond to the internet they put up their abandoned settings on the website for free download. One of those free downloads was the Nethril: Empire of Magic setting and it explains how humans became dominant in magic and why gnomes favor illusion magic. I'm not a lawyer but I don't you can take back what you've given away so you can find copies of the setting of web and *in my non lawyers opinion* doing so is legal.
Long story short - early Nethril is Rome and the elves are the Etruscans. Elves taught humans elven magic but prevented them from learning spells that could damage nature - no fireball for humans. Some human found the Nether Scrolls (later revealed to planted by the Chronomancer) The scrolls were the raw source code of magic and anyone who read them was on path become an archmage or even a demigod.
Nethril switched to the more destructive form of magic and became a empire. The elves were forced to follow suit and they stole the scrolls and started using netherese magic as well but spent their time finding ways to make it less destructive to nature. Humans on the other hand were creating paradise zones of eternal summer.
But Nethril fell and humans were divided on Magic: the Uthgart barbarians, the former peasants and slaves of Nethril -- decided to renounce all magic. It took centuries for some tribes to develop any tolerance for any magic at all.
Elves on the other hand thought they were correct. "If the humans had simply adhered to the nature-preserving restrictions we did Nethril wouldn't have fallen" Culturally humans have anti magic contingents among the Uthgart and in Amn. The high elves, on the other hand, are united in their appreciation of magic.
And it's worth noting Mystra had both Elminster and Khelben learned magic from the elves.
Tl:DR despite Mystra preference for humans, humans opinions are magic are diverse and deeply divided where high elven opinions on magic are relatively uniform: magic is art, magic is beautiful. So it makes sense that humans would get +1 to all traits where high elf would get a boost to intelligence and a cantrip.
