I don't personally have an issue with grabbing the elf stat block and saying, "this is a half-elf," but a lot of people weren't happy with that. So, if you reintroduce half-elves as their own stat block, what would your approach be?

Here's mine:

Creature Type: Humanoid

Size: Medium (about 5–6 feet tall)

Speed: 30 feet

Darkvision. You have Darkvision with a range of 60 feet.

Elven Lineage. You are part of a lineage that grants you supernatural abilities. Choose a lineage from the Elven Lineages table. At level 1, you gain the listed cantrip of that lineage, but you do not gain any of the other level 1 benefits. I.e., if you choose the High Elf lineage, you cannot replace the Prestidigitation cantrip on a long rest; if you choose the Wood Elf lineage, your speed does not increase to 35 feet; or if you choose the Drow lineage, your Darkvision does not increase to 120 feet.

When you reach character levels 3 and 5, you learn a higher-level spell, as shown on the table. You always have that spell prepared. You can cast it once without a spell slot, and you regain the ability to cast it in that way when you finish a Long Rest. You can also cast the spell using any spell slots you have of the appropriate level.

Intelligence, Wisdom, or Charisma is your spellcasting ability for the spells you cast with this trait (choose the ability when you select the lineage).

Alternatively, you may instead choose Human Lineage. When doing so, you instead gain the Versatile feature, granting you an Origin feat of your choice.

Fey Ancestry. You have Advantage on saving throws you make to avoid or end the Charmed condition.

Ability Score Increase. Choose one ability score of your choice to increase by 1.

My justification is that when you compare the 2014 Drow to the 2014 Half-Drow and ignore the other traits that elves lost coming into 2014 (extra languages for some, weapon training for all, sunlight sensitivity for Drow), the difference between half vs full Drow is that Half-Drow lost Superior Darkvision, Keen Senses, and Trance but gained 1 ASI. Half-Drow previously received the full benefit of Drow Magic, so I followed that template for the Half-Wood and Half-High Elves.

For the "Human lineage," I tried to recreate the base half-elf that had Skill Versatility by comparing it to the old Variant Human and the new Human. Giving them the Human's Versatile feature let's them emulate their old Skill Versatility (by taking the Skilled Feat) or gives them a similar feature as their elven lineage counterparts with the Magic Initiative feat, or they can choose any Origin feat of their choice. They gain a 1 ASI at the cost of Skillful (one skill proficiency) and Resourceful (daily Heroic Inspiration).

So what are your thoughts, and how would you tackle a revised half-elf?