There are few things that make “me” necessarily “me”.
One thing has to be that it is necessary that I was born of my parents. For nobody else, this is necessarily true, except my siblings.
The essence of humans is the laws of nature. The only true objects in the universe that we know of are particles. What’s below the sub-atomic realm, we don’t know. We can’t know at this stage.
I certainly reject any notion of identity beyond the biological categories. But even species is kind of arbitrary. The most common definition of species is “able to beget fertile offspring”, however, this is not true for all species. It’s more of a general rule, in that sense.
The only truths about knowledge that we know of are the truths of mathematics and logic, which are stipulated to be true once proven to be true. The logical law of identity A=A is the only type of identity, therefore, that I accept to be true. But again this is circular because that hinges on what we believe constitutes something being an entity possessing an identity. Again, only the most basic objects in the universe (physical particles) are objects.
Tables, chairs, bottles, concepts, etc. etc. are convenient ways of thinking about the world, and are also useful for pragmatists, but ultimately these non-physical and non-scientific ontological categories aren’t defensible.
You could point out, however, that even logical and mathematical truths are just a feature of the universe, something that culminates in our understanding of these ideas through the firing of neurons, which are also based in physics, even though mathematics has some very unique properties and are sublimely beautiful in many ways and seemingly mysterious, there is no reason to assume that there is a platonic realm of ideas of concepts where abstract entities and ideas are found. I’m, if you haven’t already guessed, strictly a physicalist.
Yes, this is reductionistic (and typical of non-continental philosophical discourse), but that’s just the way things are from what we understand about science. I don’t agree with constructing our ontology based on constructivist ideas outside of textual analysis and the analysis of language. When we are talking about the physical universe, this is not helpful or useful. When we are talking about why people believe what they do, what ideologies they adhere to, etc. then constructivist ontologies can be very useful in challenging and understanding the motivations behind why people act in the ways that they do.