No, there's no such assumption in my statement. That statement is merely open about what we don't know. Conversely, there is an assumption in your reasoning that non-animals are never conscious, which is, well, an assumption, and not derived from facts.

This creates a blind spot where an area of non-knowledge is assumed to be known about, and rejected out of hand. I have to point out that taking the view that consciousness is a property of animals does not exclude non-animals having it.

Even then, there will be a tussle over the exact line of what qualifies as an animal for the purpose of consciousness, resulting in the need to answer the same generalizations (e.g. intention, mood, emotion) that would allow yet undiscovered but plausible forms of life to qualify as conscious.