I think everyone here has a different issue which is part of the problem. As everyone has a different talking point, there is no actual solution.
My first issue is that two playable species which have always had their own entries, and are both very popular, are no longer getting their own entries. Instead players are being told to reflavour one of their parent species. The result being:
DM: So what are you playing?
Player: Half-Elf
DM: Ok so what race are you really playing?
My second issue is Humans and Half Elves being mechanically dull and lacking any identity on the tabletop. 5e humans are literally a bundle of nothingness, and the tabletop would lose nothing if they got deleted. 1DnD humans have fixed that and given them a mechanical identity with their ability to gain inspiration. To me, half-elves should be reworked to actually gain a mechanical identity, rather than a minor feature which basically never comes up and some skills.
And my last issue is the names. Half-elf and half-orc as names has ensured that both species have never gone and developed their own identity beyond 'what they're not'. The book entries literally spend ages saying about what the half-elf isn't, and with barely a mention of what the half-elf is. Even irl hybrids aren't called 'half-something', as they're given their own unique names. Eberron fixed this by calling half-elves 'Khoravar', and has given them their own cultures and history.
So basically what I'd like to see is:
Half-Elves and Half-Orcs given their own unique names and cultures lorewise, and given their own mechanics on the tabletop. But rework those mechanics to be actually unique and interesting like has been done with the 1DnD human.
And then people wanting to play the child of a human and an elf/orc can either use the guidance given in the playtest (pick one of the parent species and reflavour), or they can use the mechanics for these two species.
And I feel that a Mixed Origin subsystem that lets people choose aspects from between two parents would make
all mixed origin/hybrid folk less dull, because not all mixed origin/hybrid folk will be exactly the same.
Want an in-game justification? Such folk weren't created by the gods like dwarves and elves were and are less hard-coded. Rather they are a delightful amalgamation with even more variation and diversity provided by the system itself. Whether a happy surprise, or purposefully intended due to the existence of magical interfolk fertility so that it could delight the Powers That Be with what evolves from their creations.
I think it would be better that the "half-elf" nor be
directly called a Khoravar in the 2024 PH because there is nothing in the lore that suggests they would have spread throughout the cosmos to Krynn and FR and anyone's home world (not everyone's home game buys into Spelljammer or multiversal theory.) Rather, I think that showcasing the options of a elf/human hybrid would be appropriate as an example of a use of the system.
Hmmm... Is hybrid a charged term? The Simic Hybrid exists now because of MTG. If we can just get past the pseudo-sci-fi perspective of the word "Species" that has been around since the middle ages (late 14th century), and Hybrid (late 17th century) we can use both in the 2024 rules.
It could be called the "
Hybrid Species" system.
Elf/Human Hybrid example
1. Choose one of your parent's Species (Elf or Human) to provide the the Primary (non-modular) abilities of your hybrid character.
2. Select X Secondary abilities from among the modular Secondary abilities of both parents' species.
3. Select X Tertiary abilities from among the modular Tertiary abilities of both parents' species
4. Select the appearance of your hybrid using any variation of physical qualities between your two parents' species, ensuring that they have any physical characteristics necessary for the use of any physical abilities that require it (wings for flight, for example.)
5. Talk to your DM about the cultures available in the campaign, and consider what species or culture your character might identify as. Some call themselves "half-elves," reclaiming once-insensitive slurs for themselves. However in Eberron, Elf/Human hybrids have become so many, and have developed their own cultural identity, that many have adopted the cultural identity of "Khoravar," considering themselves true children of the continent of Khorvaire.