Humans quickly get a reputation among the interplanetary alliance and the reputation is this: when going somewhere dangerous, take a human.
Humans are tough. Humans can last days without food. Humans heal so fast they pierce holes in themselves or inject ink for fun. Humans will walk for days on broken bones in order to make it to safety. Humans will literally cut off bits of themselves if trapped by a disaster.
You would be amazed what humans will do to survive. Or to ensure the survival of others they feel responsible for.
That’s the other thing. Humans pack-bond, and they spill their pack-bonding instincts everywhere. Sure it’s weird when they talk sympathetically to broken spaceships or try to pet every lifeform that scans as non-toxic. It’s even a little weird that just existing in the same place as them for long enough seems to make them care about you. But if you’re hurt, if you’re trapped, if you need someone to fetch help?
You really want a human.