The logic of helping with student loans is the student loans are making them too poor. Hence the reason to help them is because they are too poor, and government wants them to not be so poor.

Logically, the government should be helping all who are deemed too poor, regardless of why they are poor.

Child tax credits are neither here nor there in this discussion, because their purpose is to be an incentive to raise children for society. Although I would prefer it to be done via straight cash also, as opposed to meddling with taxes.