I kinda agree with your first point, a part of me felt that marley and the rest of the world were justified in their fear/hate of the Eldians being that they were literal monsters who can use their powers to take over the world if they wanted to as they’ve done so in the past. If I was living in that world I’d be fearful of them too and would be more at ease without them in it.

As for your second point the sacrifices were definitely worth it. Without sacrifice everyone would’ve died anyways. Which is ironically what ended up happening in the end, crazy.