Project Hail Mary spoke to me when I watched it in theatre. It is just a well written and beautiful movie that respected the intelligence of its audience. The special effects were amazing. It had actual set design. The music is amazing. The alien was a puppet and looked like an alien. It also made me feel the intended emotion; somethings just don't do that for me.
In science fiction there is a concept of the novum. It is essentially the concept everything loops back to it. It is fair to say the Astrophage is the novum because it is the reason the story is happening. It is the thing killing the sun as it is the thing propelling the ship to complete the mission. It propels both ships. It also was the reason Rocky survived. I think is nice the problem was solved by something of the same nature: a biological problem having a biological solution.
The Astrophage problem was solved by introducing the Taumoeba because it preys upon it. Since the Taumeoba consume Astrophage, it seems likely Tau Ceti might have been the origin of the Astrophage. On Earth animals do appear in new environments on their own. Sometimes, they migrate differently because of a natural disaster. Humans are great at going places. The Astrophage is basically an invasive speciese. The mission was essentially a giant environmental conservation effort in space. Not sorry, Astrophage, don't outclass the masters.
It is fair to say major theme is people working together for a common good. Everyone on Earth at least tried to pull together enough of their greatest minds to solve this problem. The Eridians did something similar. Grace and Rocky worked together to collect the Taumoeba need to save their worlds. On that day, two worlds got saved. We all win.
Another theme is general heroism; people rising up to the challenge despite not feeling ready for it. Although Grace was forced into the mission with amnesia, he managed to get the job done despite the rest of the crew dying. He was fit for the job despite believing otherwise. Although he did not want to do it, he is all the better for it. He saved two worlds and made first contact. His students must be so happy because they personally knew the guy who saved the world with a funny alien.
The storytelling itself really elevates the film in the way it presents the events of the story. When it starts with Grace having amnesia, we discover the past with him. Him regaining the memory of him refusing the call to action when his greatest moment is still fresh on our minds really shows his progress. It helps create a great juxtaposition of the person he was on Earth with the person he has become on his journey.
Also, him venturing deeper into the unknown to save Rocky shows how important their friendship is to him. Since he saved the world, he decided to save another. When he went to save Rocky, he not only saved Erid, Rock's world, Grace also saved his new one Rocky. When he is on Erid, he finds happiness in teaching the Eridians. It is just really sweet.
A few reviewers I watch believe the film is partly so great because everything else pertaining to science fiction, and films in general, is so bad; unfortunately, I have to agree. I just wish the overall quality of the industry was better. Still, it is amazing; it should be the standard. I love it, and I still think about it a lot.