Yeah, it does mater. I don't see why he would see Thanos as anybody different then any of the heroes. The biggest genocide ever with a chance of Thanos surviving and living a life of peace and comfort on a far away planet? Plus it does not solve the issues because in all that chaos basically delivers the world to the most powerful.

If they had done that it won't be for character reasons, just another attempt to tell the peasants that the establishment is important for 'safety'

Last time I checked, people didn't found their core belief system around whether prisoners of war existed or not.

Even so, there's tangible proof of him being there, by his physical body being there, when it happened. This can be proven by science. Obviously that's not able to be proven after he was released from the camp, and yes, we have to take the scribbles on a page to know it happened.

I will give you that.

For anything that is a universal truth, like gravity, chemistry, the properties of light, electricity, and all the principles behind electronics engineering, etc.... All of that is provable. Lived experiences, history, sure. We have to accept that what we're reading is true or not. But that's a choice.

Science, which defines pretty much everything that's happening, why is happening, and how it can happen, is immutable.

The idea of "God" has no basis more reliable than someone's report of it happening. For something so universal/omnipotent, the fact that the only "evidence" that it happened is in a book, yet this God has a plan for you right now, but you can't know it because God won't tell you, nor do anything outside of what physics/Science says can/will happen, isn't evidence of the existence of such a deity, regardless of what someone calls "God".

All other things that exist, the forces that act on those things, and all of the possible outcomes of that thing existing can be proven by science. God cannot be proven, by science or otherwise.

Even history, to some extent, can be proven, because the evidence still exists. You can visit auschwitz, and see where history happened from WW2. You can see the damage from bombs and gunfire in structures that were standing when conflicts happened. There's still evidence for a lot of that. And again, the same cannot be said for any book about any deity.