Alright, so here's my go at it:
Traits:
Iron Lungs: Humans recover from fatigue faster than other races. They regain full HP on a Short Rest.
Adaptable Mind: Humans can choose one weapon proficiency and one skill proficiency of their choice.
We Stand Together: Humans can use the Help action as a Bonus Action.
I think this would make for a decently strong race in BG3. Iron Lungs isn't that strong because Long Rests are easy to come by, but I tend to use them whenever I do something daring (aka stupid) and get hurt and don't want to drag the party through the whole Long Rest ceremony and waste food. Human players being more likely to take risks and get hurt because they can easily bounce back seems flavorful to me, even if it's not very strong.
Adaptable Minds is obvious. Humans are the Many Hats race in DnD. I like weapon proficiency because it makes humans more flexible at playing different classes, which makes for more unique builds. Wizard with a halberd. Cleric with a glaive. Things like that. But you still want something nice for martials, so a skill proficiency lightens the load a bit on Fighters and Barbarians who sometimes feel useless out of combat while making human rogues some of the best skill monkeys in the game.
Help as a Bonus Action is really good in my mind. Just the fact this means you could get a party member off the ground with a Bonus Action and still attack is a big deal, but being able to remove other effects from allies in melee range without giving up your main action is pretty huge. It's also the most thematic I feel, because it represents humanity's greatest strength. Humans aren't as smart as gnomes, strong as orcs, dexterous or magical as elves, resilient as dwarves, or as chill as Halflings, but they are still the most numerous and powerful of the races on Faerun. Why? Because humans help each other. They reproduce the fastest and do the most to support their communities, which allows them to cultivate the largest territories and build the largest kingdoms. The Help action embodies all that.
It's also just nice that martials, who benefit less from Adaptable Minds, are more likely to be melee and thus can get more mileage out of We Stand Together as a result.
That's a gem of an idea, that you really hope breaks through somehow. That last feels especially apt, like making Humans special, but also charmingly mundane. Seems very on theme. I like the idea of pulling together or the capacity to be empathetic and helpful when the chips are down, even if sorta recklessly and a bit self sacrificing. Just to do some cliffhanger style grabs for the death defying save. Gives Humans a party utility for the group, similar to races that bring darkvision or stuff like that to the table.
Moving boxes around and hurling barrels as a particularly human thing to do, I mean I don't know hehe. I understand the mechanics of it from an area design standpoint, but it's kind of a curious thing to latch onto right? Maybe it'd seem somehow cooler if the bonus wasn't to the players own character but rather to their companions? Something along the lines of "teamwork" or pick-me in dodgeball, like where the idea isn't that Humans can carry the extra burden per se, but that they are just somehow better at getting the group to work in tandem, moving the boxes or barrel bombs or whatever. Basically maybe they get a quick animation that makes it look like the companion is helping to hurl the whatever wherever, with a bark or something? I could see that, where it plays more like bonus to the group with some sort of team type advantage more than an individual one. Just to capture the vibe, which I think the Help idea sorta nails.
Nice call!
