we impose meaning on the world. even the idea that each of us is an individual instead of one unit is a construct. so while we can distinguish between different biological markers, the meaning we impart to that distinction is a construct. we can draw the lines arbitrarily (and we do). the distinction of race is no more natural or meaningful than a distinction based on country of origin.
it’s too broad because it includes mosquitoes and mice and dogs and cats and fish and livestock. most people don’t treat them the same way. most ethical systems don’t treat them the same way. My ethical system doesn’t treat them the same way. so I do not agree that it’s okay to write an axiom about how you’re supposed to treat sentient beings. treating people better than animals is a good thing.
yes, I do: sentience is too broad a category, and not actually relevant to most people. if we are talking about people, then all of your statements are fine. but I don’t agree that these axioms are or should be applicable to, say, mosquitos . or mice. or dogs or cats. or fish. or livestock.
the same can be said of DNA. this is a completely arbitrary standard, and you would be better served to embrace that than pretending it’s somehow objective.