The dictionary defines insecurity as anxiety about oneself or a lack of confidence. You might even find some definitions including synonyms like humility, but insecurity and humility are not the same thing at all.
While insecurity speaks to anxiety about oneself, humility isn’t about anxiety but rather an acknowledgement that you might need to know more or get help in an area. One stems from a position of weakness and the other a position of strength.
Unfortunately, insecurity often manifests itself in behaviors that typically aren’t viewed as positive. When we, as leaders, talk down at people, make others feel less important, take credit for other people’s work, say things about others that we wouldn’t dare say to them directly, deflect blame, not own up to something, and so on… these are all forms of insecurity – all ways in which we’re really saying we lack the confidence and knowhow to behave better.
I suppose being honest with yourself so you can improve starts with getting feedback from others who are willing to tell you the truth, assuming you’re willing to listen.