Remember that feats are optional and possibly tied into the speciality system that a locks them in place with no substitutions. Giving humans an extra feat doesn't work at all with that system.
Likewise, skills are optional as well, despite being included in other races at the moment.
We've been told many times that feats & skills were optional, but given the current rules if the game doesn't use feats than
everyone should not use feats, otherwise clearly those who use feats have something more than the others. Still, feats are indeed technically optional, and the easiest thing of the game to leave out without having to change anything else. Unfortunately this is one reason why a human bonus feat may not work for that 10-20% of groups not using feats at all.
Skills are not so optional... You don't have to use Backgrounds, you don't have to give 4 skills per characters, and you don't even have to use skill dice at all,
but the Rogue at least cannot be played without skills, it just wouldn't make any sense. Thus you can play a game without skills only if you don't have a Rogue, or you can play a game where only the Rogue uses the skills mechanics. Without skills, non-Rogues characters may be
slightly downgraded (other classes have max 1 bonus skill, some races have 1 bonus skill) but still playable, but not so much the Rogue... However, technically this means skills are
not truly optional.
IMHO the best way to handle this, would be that instead of giving humans a fixed set of bonuses e.g. one feat + one skill (even tho they are already flexible because they can choose which), humans could be given a flexible set of bonuses e.g.:
- one bonus feat
- one bonus skill
- one bonus proficiency
- a +1 to one ability score
- one known cantrip (any class)
- 1-2 extra known spells (only if they can already cast spells)
- one extra maneuver (if applicable to the class)
- one extra skill trick (if applicable to the class)
- ...
And then just say "
pick any 2 from the list". Maybe even allow to pick the same thing twice, i.e. +2 to scores or 2 bonus feats!
This way, it would be
impossible for a group not to be able to use such version of Human, because in the worst case at least ability scores will be used in their game. It would also make for a truly
versatile human race!
Skill Focus would be the most applicable feat, able to benefit every character across the board equally (IMO).
For a fixed feat, I would go with
Toughness (tho I am not necessarily a fan of the current version of it). It makes a lot of sense to give extra HP to a Basic PC, since Basic is more often than not going to be the choice of a newbie, and HP are certainly used in every game.