If you literally have "no idea where we can draw a line", then you're begging the question by even talking about "creatures that seem highly likely to be on the

If you literally have "no idea where we can draw a line", then you're begging the question by even talking about "creatures that seem highly likely to be on the same of the line." You don't know where the line is, so you can't know where creatures stand with respect to the line.