I've had cats much of my life as well. And I relate to what you said about some people not realizing how they bond with humans. It's hard to explain my thoughts...they want to connect with their human companion and you have to reciprocate. I say "companion" because one does not own a car, at best they see you as equals, sometimes they own you

I had a 10 lb. Siamese from kitten ,until he passed at 16. I'm 20x his weight, yet he would herd me toward his food bowl by putting himself in front of my stride and correcting any step not in the direction of food with his 10 lb body block. He passed about a year after my dad's passing which was about a year after my mother's passing (all three of old age). Then it was just me and my other cat, a big 18 lb tomcat. I did a lot of yardwork around the house that year just to keep my mind busy while going through the grieving process. Any task I was doing he would stand beside me and watch. He wasn't distracted by chipmunks, squirrels, nor birds. It was as if he was being my guardian through my grief and maybe I was his too after losing his brother.
I can see that you and Elvis have a similar bond. His posture, relaxed, head upsidedown. Oscar used to do that. It was a show of trust, guard down, "let's chill out together".
On a lighter note, have you ever seen the old EDS commercial, "Heading cats"? I find it hilarious. So well done. I see some new detail every time I watch it.