Late to the party, but I just watched it yesterday.
I liked it. I loved how the movie structure parallels understanding the language. It doesn’t just spoon feed the story of learning to communicate, it makes the viewer “learn” at the same time.
To addres the biggest comment in this thread, it’s not clear from ther movie if Louise sees her entire future, or just snippets. If it is just snippets, then if she were to try something different with Hannah, like waiting a while for her to be born, or doing testing, that doesn’t mean it will work. The forward-memories were not date stamped. As long as she chooses to have Hannah, then her visions are accurate. Maybe whatever she does, is what she did.
Additionally, she’s just one data point. Maybe it is totally possible to alter the future, that what you see is just one possible future, and with more experience you can learn that. And if she chose to not have Hannah at all, or not call the general, then her future would be different. Perhaps the aliens know this, but just can’t, or won’t, communicate that fact. Maybe they want/need us to discover it on our own. (Or, maybe they don’t. If we also learn that the future is not fixed, there’s a possibility we might not help them in 3000 years.)
Humans having precognition isn’t a new concept. People have always claimed to be able to see the future. It’s always been dismissed as delusions or fraud, but in the universe of the movie, maybe they weren’t all wrong. Seeing the future, or a future, is within human potential. Maybe a complete understanding of quantum dynamics would show that human thought shapes reality (it isn’t the observing of the cat that determines whether it is alive or dead, but you “deciding” whether it is alive or dead that settles the question.). More human experience with the ability will explore these questions.
Even so, if there is only one fixed future, that, too, is not a new concept. People have been wrestling with the concept of predestination since it was first expressed. The biggest question being, if the future is set, why do anything at all?
For other sci-fi examples, in James Blish’s story “Beep”, it is definitely shown that the entire future is fixed, but yet, people still act as if it isn’t. That universe even has time travel, and why one would need time travel in a predestined universe was a mystery even to the people that understood it.