I'm now going to defend The Tomorrow War by dismantling the criticism I've seen on social media. Wish me luck. Rule number of of time travel paradox movies is that it's a paradox. As such the ending will always seem contradictory.
At the beginning of the story, travelers arrive from the future and announce they are the few remaining survivors and blah, blah, blah.
Notice that the story then skips forward by a year.
Also remember that time continues to flow.
Therefore, any sensible response that you can think, of has happened.
For example. We now know that time travel is possible and we start researching how to make a machine, because why wouldn't you?
We also know in passing that the world's militaries rally the troops and send them forward to fight.
A Year later the losses are horrendous.
Thirty years of preparation go by, but guess what? The aliens don't land in a fancy spaceship, and have bred vast hordes in the faraway places, and before you know it countries start to fall.
Okay, that's a bit farfetched, but assuming no one goes nuclear, it's as plausible as World War Zombie.
The creature breed like rabbits, eat like locusts, and by the time the nuclear option is on the table it's too late.
But at least they have the time machine, and can go back and try again.
We have a hint that this has happened because the heroes daughter tells him how after he came back from his week long tour he was a changed man.
And there's the paradox.
Each time the machine is used you get a slightly different outcome until the time comes when you solve the problem.
Really, is it all that hard for people to see this?
Have at it, roast me social media.