Contractarianism is a moral theory saying that moral rules are a sort of a contract, and therefore only beings who can understand the terms of the contract are bound by it.
So, strictly speaking, moral rules should apply only to behaviour among normal adult human beings, but they could be extended to also cover beings that the people who entered the ‘contract’ care about, like their children for example, for reasons of indirect duty.
Other groups who could be protected by the moral rules of the contract in this indirect way are, shall we say, the groups protected by ‘political correctness’, that is whoever the majority of the human population cares enough about or anyway whoever it is considered a duty to care about by what happens to be the current ideological orthodoxy.
One problem with contractarianism is that it betrays the very purpose of philosophy.
Since its beginning in ancient Greece, philosophy has always had the role of challenging the ideas currently held by the majority.
A moral theory that, in principle, simply justifies and accepts whatever the majority happens to believe is more than a philosophical failure: it is a complete redundancy. People do what they like to do and what they’ve always found it easy to do anyway, there is no need for philosophers to pat them on the back and say: ‘Well done!’.