Awesome Exodis, while criticizing ideas is hard, I've had practice recently.
The first piece is your old fashion Alien invade the Earth and are about to enslave. But you've clenched onto what makes this old fashion thing so successful, the idea of the Hope/Faith theme. Here you have the idea that our time is about to be brought to an end by a much superior force that we have no say against, just like things like Global warming, economic crisis and more smaller things that mean our own end like diseases or threats. However, there's always holding onto that little bit of hope, no matter how impossible or irrational it seems, if you hold onto it, it can give you strength at least. Like have a cure to an incurable disease or having such an job that seems unlikely for you to get. Really this thing can be argued and played with, as this general theme is like the Humanistic Self-image theory which you'll have to look up instead of me getting into a psychological rant.
So overall you're going with a idea that is retro from it's popular days in the 90s era with a theme that has made it wondrous. So so far great job. Though I had you make the aliens something else but technologically or biologically advanced (Or just advanced in general) or have unlimited resources as those are just being overused. You could go with it in a Shonen fashion where they're able to control energy like they do in DBZ or outmaneuver and outwit us due to their warfare experience or they've been able to turn humans against each other by diplomatic cunning and sabotage. Fair enough if you do want to go with the advanced thing as the reason it is used is that again, makes aliens seem unstoppable and hence we seem to have no say in our future, where there are only tiny beads of hope for a hero to raise up.
I've just been hammering away at this anyways because all you've giving us really is a summary. If you want advice about characters though, one thing I find, but not definitive, is if you want your main character to be relatable or a role model. They can be both, but characters tend to lean more towards one of the other. For example, one of the big thing that divides DC and Marvel, is that nearly all of DC's characters are role models and Marvel is nearly all relatable. In your case I think you want to go for the Role model, give him traits we want to look up to and inspire us. Though if you want to make him relatable, give him trait that can be related to general issues and deals with symbolic challenges.
Anyways hope this was helpful and you were able to read all of it.