Is there an easy way of adding a feat to a human character in an editor? Just to sort of "force variant human"?
There is existing code to make variant human work. Half-elves already get to choose two ability scores to increase and feats are chosen in the ASI screen. So it'd be something similar to giving humans a toggle to trade half-elf ability score choice for +1 to all scores. Then, in character creation, add a path to the feat selection screen.
The toggle would need to enable: Trade human ASI for half-elf choice & Move player to feat selection at some point in character creation. (Logically before creation of who the player dreams about).
I'd be surprised if there was any code blocking characters from having a feat at level 1.