SPOILER ALERT: This was probably discussed before but if the Aliens did indeed come to pass on the 'gift' to humans, why did they leave as soon as the worldwide strike on their ships was called off? Did they just assume that the entire humankind will cooperate and pick up on what (they probably on were able to infer) Louise had learned?
What were they really hoping to achieve by passing on their gift to humans? Surely by the time they left only Louise seems to have actually learned to navigate time the way they do.
Aliens' premise seems really far fetched to me. Consider the two options
a.) Only Louise learned to use their weapon (language)- how are they sure humans 3000 years will return favor? Based on the future flashes towards the end, it still seems like Louise is still teaching all of this in her classes, meaning it's still at the very best an exotic skill, so aliens left sooner than they should've? Why did they leave if they're able to infer that humans won't learn the skill on a wide scale right away.
b.) Entire humankind will be able to navigate time- peaking into future and looking back into past the way Louise does. Did they really assess the implications of human race on this?