I do think that’s true, but largely because animals mostly don’t have the luxury of being out of survival mode. They can’t have unforced discontent when it’s constantly being forced.

I’m sure the ancients were aware that animals suffer. I think it’s noteworthy that the passage in Luke was talking about plants, not animals. It’s hard to imagine effort and discontent in an organism with no brain.

In any case, I’m definitely not taking life advice from an apocalyptic cult telling me not to plan for the future and give away all my possessions because their god will provide.