The aliens who arrived need our help in 3000 years?

In 3000 years it was probably humans that were pains in the ass trying to fight them with space nukes after we mastered interstellar travel. Them teaching us this language changes our path and makes us friendly by then instead...

3000 years from now, there'll be a mass famine on planet squid.

Humans will come along.

Nom nom nom.

First, I actually really like that it is vague and nonspecific about what the aliens will require in 3000 years. But it is clear that they have "solved their problem" by involving the humans and gifted them the Universal Language, which will rewire humanity's brain to view time as non-linear.

I would suspect that the Heptapods are without ego and have no real need for concepts such as "more advanced" or "less advanced" but are more concerned with enlisting the support of another intelligent civilization who can be a part of a solution to whatever problem they are having.

What can the human race offer? It's difficult to say for certain. Perhaps the heptapods are few in number and they need vast numbers of people for something. Perhaps they will need the humans to build something. I personally like that it is an unknown, it doesn't really matter to the story itself.

It's not really important. What is important is the knowledge that, should humanity survive this little incident, it will last a further 3000 years, and that the tetrapods are manipulating events through time to benefit themselves. What 'help' it is we provide is something we cannot know OR understand in the present.

They lost their car keys but remembered last having them on Earth.

Some already covered....
TL;DR, smart people can be really dumb sometimes

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Humans have domain of life on earth, but we're still learning from animals. Examples include but not limited to how we studied geckos to apply their scaling and sticking abilities. How hummingbirds fly. Their body parts and secretions for research into medicines, etc.

It's possible the aliens will go through internal strife or politics that keeps them from progressing (that's the main reason why humans won't get far :( )

In human nature, smart and/or experienced people are revered and get much accomplished, but sometimes, a newcomer comes in and shows the rest new and novel ways to get things done (don't even need some young, fancy Ivy league degree for that). It's possible humanity has some creative and innovative ways that the aliens wouldn't be able to execute.

In 3000 years we will be superior than those puny aliens that become "in a dying phase" from a bit of C4.