How you understand your chessability increase?

I know that although "AI could not determine the human's real power", in lichess you can use some indicators such as "blunder" and "mistake" counts in games. I am considering these are the good indicators of being a good chess player.

If they decreases, then that means you are more familiar with "pitfalls" of tactics and apply good ones and new and error free maneveurs in front of your opponent.

I will look that whether there is a statistics of mine in lichess which shows my blunder/mistake levels in games! I hope :D

Chess is a game to practice even more serious real life things, such as "thinking a tactic/ plan/ trick", "setting a game"... nearly all of elements included in Sun Tzu's book. So if you can find a good indicator in chess, then you can rise your confidence level to do "anything" in real life! Because as Kirksaid in Star Trek II : "I don't believe in the no-win scenario.", I am too!

That is my opinion :D.