They're not talking about the economic value of humans or even the psychological value of humans as subjects with experiences and a right to liberty or care or something. The idea they're trying to recall and reinvigorate is a sense of human value that transcends that temporal, material noise altogether and that is truly universal. It's the human value that welcomed slaves, prostitutes, wretches, merchants and kings as peers in something grander than economy or state or lineage or tribe or creed.
Now, you can make a well-developed case that that's hogwash and that the human value that matters is the one that alleviates suffering or grants liberty or even the one that grants material reward for some virtue or bloodline or whatever, but that's not what these guys are talking about. They mean a human nature that is always there and always worthy, just as much when it's experiencing temporal poverty/suffering/abuse as when it's basking in temporal wealth/success/freedom.
The idea is that Christian or not, Catholic or not, it does good for everyone to think of human value that way and the critique -- for a long time now -- is that for all the flash and glimmer of technology and its material benefits, it sometimes makes it very very easy to forget.