The reason for caring for others is that others cared for us.I'm not sure that motivates everyone - and certainly not everything, (and humans aren't the only species that help each other). There is still the vexing question that you don't need to reciprocate to receive help. However, you could argue that it is indirectly true because one evolutionary criterion for fitness can be caring for each other. Cooperation may be another way to put it and directs thoughts towards how much more a group of cooperating individuals can accomplish relative to an isolated individual. Cooperation is a well recognized feature of evolution (e.g. - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3279745/#__ffn_sectitle - Five rules for the evolution of cooperation by Martin A. Nowak) although you'd hardly recognize it with the almost singleminded focus on violence and competition, even in so-called documentaries on nature - "red in tooth and claw". If cooperation is a desirable trait, you'd expect at least some species to cooperate - as so many do.
As we expand who we help, who we educate, more people will be able to use their skills effectively and find their best fit in the world. As we do this, people see a world of hope where their children will survive and help each other, educate each other, empower each other.That makes sense to me and is a small part of what we may consider to be behaving responsibly. Another list of ways to care would encompass the behaviors we may call moral. Morality is about treating others well and discouraging maltreatment which likely contribute to a stable and productive society. A thriving society rather than one that merely 'survives'. Evolution has resulted in genetically controlled brain wiring to perform a myriad of different functions. Is it not possible that our brain wiring also evolved to express morality because morality expresses functions that improve our ability to integrate into a more complex world that improves our abilities to survive and thrive? Evolution is about so much more than the popular notion of fighting for survival. There are better ways to evolve. We found them but largely fail to acknowledge them. Know it or not, we are moral because our brains are wired that way.