Human decency is not derived from religion. It precedes it.
Christopher Hitchens
Margaret Mead said the sign of civilization was finding a skeleton with a healed broken femur.
That means someone cared for them through the healing process and even had enough resources to feed them and keep them safe through what would have made them an easy meal as prey otherwise.
That is partly true and partly not true. Our (and some other species' ) biological decency is called altruism by scientists, and typically is extended to kin and individuals who are well known to us personally, like tribe members. But the wholesale extension of that consideration to strangers is largely a result of religious (cultural) interventions that took place after the invention of agriculture.
While there is no clear line that can be drawn between nature and nurture, because they both feed each other, religion modifies and extends our evolved capacities to accommodate personal psychological needs and social cohesion in modern, complex societies.
Hitch was either ignorantly or deliberately oblivious to certain aspects of science that didn't support his narrative (he admitted he would hate to see religion go away, because then he wouldn't have a career) but the science has only gotten stronger since his passing.
Welcome to the fray!
What does a new-born know of other people? Isn’t he or she entirely selfish?
A newborn? A baby can't even control it's own arms and hands until about 3 months.
"Human" decency is a trait of all species. Altruism is an evolutionary advantage. Even microorganisms cooperate and work for the good of the species. Some bacterial species release small molecules to scavenge iron needed for their growth, boosting its availability for their neighbours. Others produce enzymes to degrade antibiotics, protecting the whole colony. Bacteria obviously do not practice religion.
Our instincts to help one another may be reinforced by some religions, but they predate it by eons.
(Unfortunately, our tribal instincts to hate and fear strangers or outsiders are also evolutionary adaptations which predate religion. These are the dark side of altruism.)