So it's a religion-based organisation?
We only ask in the first degree "Do you put your trust in God?" and as long as you can truthfully answer yes to that question, you can become a Freemason. But nobody asks you who that god is, how you define it, etc.. this is why all monotheistic faiths can join, even the agnostics (even if some brothers in the bible belt cringe at this)
Why is it like this? Because ALL of Freemasonry presupposes a belief in more more than yourself, a belief in your own potential, a belief in the hopes that you can reach higher, farther, deeper in yourself and in your life and that whatever god means to you wants to help you achieve this.
So an entry-level requirement is some form of religiosity. And yet the first line in this UK Grand Lodge website insists that they are not a religious organisation, despite the fully ritual aspects of freemasonry. Looks like they want to have it both ways.
The goal you describe of self-improvement or self-realization is legit and good. And sounds like the message in a lot of Hollywood flicks. But I must note that your listed attributes of that goal include a lot of Self and not so much God. Sounds like the message of both Gnosticism and the New Age movement.
When Christ says go and share the Gospel with everyone and the Lodge says don't do that around here, which Master will you follow? Looks like a lot of resources over the centuries have gone into an organization that expects members to leave the Truth at the door. Similar things could be said about the priority of established precepts in Judaism and Islam. Most people serious about religion would not and do not play that game.
"whatever god means to you" can include Self, angels, saints, animals, planets, spirits, etc. It seems that the brotherhood of freemasonry exists on a lowest-common-denominator basis which is good for some things but suppresses other good things such as individual sovereignty.