There are evolutionarily-created biases, which often counter each other. So, yes, it's part of human nature, but so is a sense of fairness. Cultures differentially encourage and build on these native biases in different ways.
A deeply historically-entrenched class system is to a natural hierarchy bias is as an ocean is to a pond. I grew up in the UK, and the upper class were quite literally a different type of human, placed by history and the structures of society above us in every way. In my local town, even their school was physically placed to look over us. They spoke with different accents. Their schools were allotted places in the top universities. We were allotted places in local farms. Their failed children were given positions (often in the old colonies) which guaranteed them lifelong ease and comfort. This was all a long way removed from 'natural hierarchy'.
A deeply historically-entrenched class system is to a natural hierarchy bias is as an ocean is to a pond. I grew up in the UK, and the upper class were quite literally a different type of human, placed by history and the structures of society above us in every way. In my local town, even their school was physically placed to look over us. They spoke with different accents. Their schools were allotted places in the top universities. We were allotted places in local farms. Their failed children were given positions (often in the old colonies) which guaranteed them lifelong ease and comfort. This was all a long way removed from 'natural hierarchy'.