Instead of the elves being the oldest race, sometimes I think about a setting where they're the youngest. They seem like "humans, but better" because they were specifically created to be humans, but better. Less fey and more replicant.
This echoing of human characteristics happens naturally, as elven fates entangle the fates of humans. Humans are a special fascination, even while other humanoids are of interest. Humans − and even the wellbeing of humans − are central to elven longterm plans.
Since the elder elves are elsewhere, the younger elves are young, discovering the world around them for themselves. Elves consider this personal exploration an important part of the growing up process.
Each generation can see fresh insights into the world. When becoming adult, they keep the rest of the elder elves in tune with the realities that are going on.
If elves had a slogan, it would be "Live slow, die old."
I view elves as highly industrious, and innovative, mainly with regard to magical research. Most of their magical accomplishments remain within their elven communities, including each fey court, with access restrictions beyond elven communities. There is a kind of magical arms race. The elves direct their magic advancements toward longterm goals, but spin-off comforts are in casual use. Not only arcane innovations, but every power source: arcane, divine, psionic, and primal. These sources help toward the engineering of fates of worlds toward the longterm goals.
The curiosity about the magical sources eventually led a branch of them to materialize into the material plane to become creatures of flesh and blood, in order to investigate the martial power source. Whence a faction are gishy elves now harmonizing magic and martial.
For my Homebrew, the elves and dwarves were the creation of the Angels that were created by the first Gods. As such, they have roles in history and divinity. Essentially, the first intelligent creatures were Dragons. 15,000 years later we saw Giants created. 6,000 years later we saw the creation of Angels. Then, the Elves and Dwarves are created 500 years later. Gnomes, Halflings, Fey, Aasimar and Tielflings follow 700 years later. Then Orcs and Goblins 1300 years later. Duergar, Drow and Gith spawn about 2000 years later. Following that, there is roughly 1,000 years before the majority of the remaining races are created by the Gods (which was about 3500 years ago).
Essentially, Elves and Dwarves took over the Prime and had 500 years to 'conquer' it. Then they saw other races introduced over 5000 years, but they were the two dominant medium humanoids for those 5000 years (really more like 7000 years) before other heritages began to overtake them. In a sense, they built the historical world that is the source of all of the ruins that are explored in adventures. They are the builders of my dungeons.
My campaigns view the dwarves as "anti-elves". (The dvergar are also fates, like alfar.) Where elven magic associates more so with success and good fortune, the dwarven magic associates more so with futility and ill fortune. But inflicting ill fortune on a dangerous enemy can be useful, thus dwarves tend to make the best magical weapons. Some dwarves are ironically called "elves" because of how helpful their curses prove to be.
Now that ability score improvements are part of ability score generation and no longer part of race selection, it is much easier for a dwarven culture to master magic. So while there is a Tolkien-esque martial dwarf culture, there is also a Norse-esque dwarf culture that is especially known for magic.
The successful fates of the elves associate with the positivity plane, along with the fey plane and elemental air-fire. Oppositely, the futile fates of the dwarves associate with the negativity plane, along with the shadow plane and elemental earth-water.
The shadow dwarves tend to be the same heights as humans, but with deathly complexions. They are also goodlooking, but while they arent undead, they have that vibe. They spend life entombed within rock and only venturing onto the surface during a thick fog or a dark night. They sometimes shapechange into animals in order to be in direct sunlight. They feel affinity with other dwarves, albeit tend to spook them.