Well, ideas are not entirely original. Its possible that multiple people can have the same or similar idea at the same time without any knowledge of the others.

But in general I think that many ideas are stolen from other cultures and put forth as original, yes. And usually if its taken from anime, its probably because the audience its being presented to would refuse to watch it purely on principle of being anime specifically. Theyre fine with Disney Dumbo and Pixar Toy Story, but for whatever reason Japanese animation is crossing the line. Anti-anime people are weird like that.