I’ve always argued that if it wasn’t for humanities automated defence systems going haywire, humanity would of been able to weather the initial storm relatively well and it’s hard to argue that the automated defences aren’t still the dealiest things around regardless of if you agree on the first point.
The technology isn’t completely lost either, there are still working computers with stored information, books and working examples that can be reverse engineered. People wouldn’t have to be rediscoving everything from a stone age level of understanding, it would quickly become a priority to anyone in power with a vision for the future that as much of this information is retained as possible and people with working knowledge of it held in relatively high esteem. It would probably be the single job catagory you’d find yourself in that wouldn’t require you fighting at some point or another, pretty much anyone else would be considered a combatant and required to act as such.
For humanity to survive would require some quite drastic changes in how things are done and how people live their lives, society would by necessity be far more militant and regimented with little person freedom. Practicallity would be valued above all, peoples lives would be very demanding and harsh by modern westen standards and individuals would be considered far less important then the collective.
Fortress cities and settlements, either above or underground, would probably become the norm. Think great walled cities with heavy artillery, sharp shooters and search lights on the walls and towers. Priority would be given to training up combatants, food, ammo, weapon production, the refinement of these four things and their improvement.
People would be indoctrinated from a young age that humanities survival is the highest priority and that their ultimate goal is to retake the planet from the invading outsiders, dissenters, I imagine, wouldn’t be tolerated in the slightest.
