> I have never come across a Buddhist source saying that some people are inherently more advantaged than others.
That's essentially the entirety of the Buddha's teachings on karma. I haven't the time to look for sources right now, but I'm pretty sure the close disciples of the Buddha - who all had distinct and extraordinary abilities, either feats of memory or meditation - were explained to have those abilities due to intense work in past lives. Indeed, the Buddha himself didn't chance upon his enlightenment - he made a vow to do it thousands or millions of lifetimes prior, and worked towards it life by life until he was able to achieve it.
That's essentially the entirety of the Buddha's teachings on karma. I haven't the time to look for sources right now, but I'm pretty sure the close disciples of the Buddha - who all had distinct and extraordinary abilities, either feats of memory or meditation - were explained to have those abilities due to intense work in past lives. Indeed, the Buddha himself didn't chance upon his enlightenment - he made a vow to do it thousands or millions of lifetimes prior, and worked towards it life by life until he was able to achieve it.