Lean respect for people principle is somewhat difficult to grasp in first place. While some gurus say it is not (only) about saying hello, I do think respect for people definitely starts with the basics of politeness, especially saying hello.
Respect or signs of reverence have long been unidirectional, from the lower ranking to the higher ranking, from subordinates to higher authority.
The mighty demanded respect to show how mighty they were and the lower ranking paid respect to the unquestioned power, especially when they were on the pointy side of the sword.
Everyone having been on the modern form of the pointy side of the sword (whatever it now is) understands that not been greeted or not been returned a hello is a deliberate sign showing some (real or pretended) distance.
Still in our days many higher ranking believe it is not necessary to say hello, return a greeting or simply be polite with “lower rankings”.
Respect for people is therefore, at least for me, recognizing the other as a peer, regardless of conventional or social ranking. Being polite is recognizing the other as a peer and showing him or her respect and saying hello is the very first polite sign to give.
When it comes to Lean Thinking and working to improve a process, the gathered talents can come in many forms and are all welcome. Original Lean did not come with grades and belts to show some kinds of ranks but put very different talents together to solve problems. And it usually works fine, especially when participants don’t have to care about (artificial) ranks or social differences.