True, that is why I added the "quite possibly." If, however, you look at "success" through an evolutionary lens things we don't get many excuses.

Things are nice and simple if you are a squirrel. Get as many offspring to reproductive maturity and you are a success! You have no control over genes and instincts will care for the rest.

If you are a human you get no such luck. You still have no control over the genes and you still have to trust to instincts, but people can make decisions about things. Thus we have to also replicate the ideals that led us to have children. That is a tricky business and is fraught with a million ways to fail especially since they will also take in information from the culture and in the end will decide for themselves.

So with humans replicating genes isn't enough for success. We don't know if ideals have replicated till our kids start raising their kids the way we raised them.

We can Intuit that just having a bunch of kids isn't enough for evolutionary success among humans. Everyone probably knows some big family that inexplicably (or perhaps very explicably) didn't result in many grandkids. Contrariwise, there are only children who went on to be the start of a large thriving clan.

The complicating factor is that we aren't just individuals, we are functional parts of society. Our ideals can live on even if we are unable to have any or many children of our own. This is a huge function of priests and religious. They may not have children of their own, but they help perpetuate the purest form of societal ideals that allow us to thrive.