I had this discussion with my work colleagues before COVID was a thing. I asked the question along the lines of "If aliens were to come to earth and pose an existential threat could you see the world uniting as one"
I don't believe so. I think although we would weakly work together the big world players still could not put aside their issues and trust enough to get the job done.
Then COVID occurred and I brought this question back up citing that even a global pandemic couldn't generally get us to put aside our differences and work for the benefit of the world.
In the back of each countries head would be "How do I as a country emerge from this threat as the dominate force".
Yeah I see what your saying and COVID did test us like never before but;
-We had a nation blatantly allow their citizens to spread throughout the world (I assume because they were not wanting to admit they had a problem).
-We had a somewhat coordinated effort (but was thwarted due to political gain/manouevering in a lot of countries).
-I think the selfishness, at least in my country started pretty much straight away. And made it harder the whole way through.
These points above, in my mind were enough to show me that we really can't together when it counts. Another example is global climate change, we are staring that in the face and we still can't get it together.
I imagine seeing on the news NEWSFLASH: Aliens have arrived and seem threatening..... We wold have;
-One country trying to make friends with said aliens to gain an upper hand.
-Another country trying to be the worlds hero and go it alone by attacking them.
-Governments quickly trying to take their chance at gaining their last bit of control by clamping down on citizens.
-Nations trying to help themselves only and foregoing other nations (eg. Yeah nuke that nation to save ours)
I do hope we do better but past experience doesn't give me hope.