Hello Borut,
Really appreciate all your comments. I'm responding to this one because it's the most interesting to me, and I can't respond to all :)
I my mind, we can have a healthy high self-esteem which doesn't need to be based on accomplishments or inflated in a negative sense. I think this kind of self-esteem stems from self-compassion and knowing we're doing our best, even if we "fail." In other words, this is the absence of thinking that there's something wrong with us, which I see a lot of people around me have. From my experience (and according to psychology, see the theory of positive reinformcement), this is a better motivation to change than self-loathing and feeling like I'm "not enough."
I imagine this is the kind of self-esteem that Siksika people have / had.
Curious about your further thoughts, if you want to share :)