Camp Camp Space Au: Nobody asked for it but I'm giving it to you anyway because I can do what I want and you can't stop me!!!
Space au where David and Gwen (plus mishap group of aliens) fly this (lightly) illegal ship that teaches kids to be "species ambassadors". Lightly illegal because it's a program Campbell made to train kids to be space pirates.
Unfortunately for Campbell though, David takes the whole programs cover-up story a little too seriously and actually teaches kids "the importance of kindness and acceptance" and "how to all get along" in addition to highly specific training for all jobs on a spacecraft. General stuff, yknow?
Anyway they land on this completely normal and unassuming planet for a routine supply run when- uh oh- David and Gwen hear that a rouge human is on the planet and HIGHTAIL it out of there. Primarily because humans are these crazy venomous highly-endurant terrifying creatures that very few have ever spoken to, and the ones that have are all six feet under right now.
So Gwen goes "absolutely not" and guns the ship filled with young children as far away from that monstrosity as possible.
Naturally, a particularly cynical, mildly malnourished, terrified out of his mind, and VERY angry human has managed to sneak onto the ship undetected. I'm talking about Max in case this wasn't crystal fucking clear.
Poor Max was mistakenly picked up by some unfavorable earth-dweling traffickers who promptly realized they could NOT handle a human, dumped him on the nearest planet and ran away, tails between their legs.
Max is now INCREDIBLY angry to not be on planet earth, and also very hungry because those damn traffickers had no clue what to feed a small human child.
Naturally, the first thing David does when he sees Max (human child) is go into DADVID mode and instantly adopt him. While speaking an entirely different language to him. Hense Max freaking out when some random red alien starts cooing at him.
Gwen finds out and opts to not put the lives of 7 children (8 if you count David) in danger and gently throws Max into a holding cell. Cue Max getting terrified AND angry.
So Gwen calls in two kids who weren't supposed to be enrolled into the program for a fair amount longer, but are necessary to keep everyone alive and happy.
Neil: who has studied human biology and social patterns (for this i need you to imagine playing the Sims for 10 hours then deciding you know enough about human social patterns.)
And Nikki: who is acting as our cross-species communication! She is also very excited to see if humans are actually venomous acid-spitting carnivores who can rip apart anything they put their mind to!
Which can't at all go wrong, right?