Why is it somehow still valid to make statements along the lines of “X is what makes us human”? Whether that X is tool-use, or a sense of right and wrong, or opposable thumbs doesn’t make much difference; it’s pretty clear that you can change this slightly to say that X is “what makes me human”, and making human is not much better than “what I want to talk about”.
Usually when I come across this in a book or an article, there is some caveat, so that though there is room to introduce some other point (as an example, for tool-use, there might be a discussion of beavers building dams, or some other non-human example of technology), this is more or less dismissed with the old medieval philosophy method whereby if you meet a difficulty, you make a distinction. So now there is real tool-use, and whatever beavers do. Silly beavers.
How far are we from a proper estimation of what it means to be human that we have to introduce some sort of test? Testing inevitably implies ranking and exclusion, so why do this? Whence the sense of being threatened by beavers, dolphins, or whatever other example of non-human intelligence that we meet?
That’s just one type of objection to the above form of quasi-philosophical statement. If you transpose some of the above terms, you get a sense of just what’s up. Suppose somebody in a conversation said, “Well, X is fundamentally what makes me a man”, you might well question their attitude towards their own self-worth, women, gender, sexuality, and all that. What masquerades as some attempt to get at the essence of a thing in actuality points away from it. This is why analytic philosophy cultists have issues with what Ayer saw fit to dismiss (and many still do) as ‘metaphysical’ statements. They achieve the exact opposite of their purported intent. Rather than getting to the ‘essence’ (yeah, whatever that is), they instead blithely assert.