Animal taxonomy is also a social construct: phylum, class, order, family, genus, species are all labels that we have created and not an intrinsic property of animals.
That last bit isn’t true, species are not a social construct.
They are to some extent: there are hybrids, rings, and other edge cases.
Social constructionism isn't an argument, some social constructs are more useful than others so you need to argue why race is not a useful social construct (which I happen to agree with)