Who came up with the 'life-debt' concept between Chewie and Han? When was that added?

I've never liked the idea. It takes Chewie from a capable and intelligent partner to Han Solo, and makes him a servant. It places him as subordinate to Han, and makes his race seem backwards. (Luke 'owes' Han his life twice, but doesn't have the backwards notion he has to be Han's servant. Human's are too advanced for that).

At best it makes Chewie a 'noble savage' type, with all of the racist and imperialist (no pun intended) baggage that carries. The debt also carries over to Chewbacca's kids... who are apparently hereditary slaves of the Solo clan, despite how many times Chewbacca might have saved a Solo's life.

I don't beleive there's a hint of 'life debt' in the movies. I just see two partners and friends who are equals.

And let me add, no matter how the Han Solo character treats or views Chewbacca, it has no bearing on my opinion that the 'lifedebt' demeans the Chewbacca character and the Wookiee race.