Taxonomy is essentially building a metaphor or analogy. It's useful at times, but it often breaks down when you start looking at it too hard.
Take everyone's favorite example: the tomato. We get into all sorts of discussions about what is a fruit, a vegetable, botanically or culinarily, etc, etc. Ultimately realizing that all plant matter is categorized as "vegetable" on the most abstract level. Thinking that one more layer of taxonomy will neatly box everything.
But it won't.
We call the iPhone a phone, but is it? I can call people from my laptop, my tablet, etc. I can watch videos and play music and write notes on my phone. Everything is everything, and nothing is what it is.
Classification is one of the hardest things because it's entirely a fuzzy problem.