Pre-Sundering, humans existed but high elves/blood elves did not.
Around 15,000 years ago, the vrykul of the Dragonflayer clan believed that their gods had “abandoned” them, and a certain time after that, some of their children were born “weak and ugly.”
Re: https://wowpedia.fandom.com/wiki/Human
The Great Sundering was a cataclysmic event that shattered the continent of Kalimdor approximately 10,000 years ago, at the end of the War of the Ancients.
Re: https://wowpedia.fandom.com/wiki/Great_Sundering
When the night elves adopted druidism, they outlawed the practice of arcane magic. The use of its dangerous powers was punishable by death. However, many Highborne loyalists of Queen Azshara survived the Sundering and grew restless. They suffered from magical withdrawal, and 7,300 years before the invasion of the Horde through the Dark Portal, they spoke against Malfurion Stormrage and the Druids
Dath’Remar Sunstrider, the leader of this movement, declared the druids cowards for refusing to wield the arcane. Malfurion and the druids warned the Highborne that any use of magic would be punishable by death. Yet, in an attempt to protest the druid’s law, Dath’Remar and his followers unleashed a terrible magical storm upon Ashenvale
The druids could not bring themselves to put so many of their kin to death, so they decided to exile the reckless Highborne from their lands. Sunstrider and his followers boarded a number of specially crafted ships and set sail upon the seas. By now the Highborne were glad to be rid of their conservative cousins and free to practice the arcane with impunity.
None knew what lay beyond the Maelstrom, but they eventually found the Eastern Kingdoms and formed their own magical realm. They abandoned the concepts of Elune and nocturnal activity, embracing the sun instead. They would soon become known as the high elves.
Re: https://wowpedia.fandom.com/wiki/High_elf