Denis, bro! I'm going to hit you with some tough love and give you a bit of a mindset shake.
The mindset you describe is flawed! I don't know who told you this is the right way to do things. If you think you are unimportant, then your work is unimportant, and everything you do is unimportant. If you were unimportant, why would people give you any attention in the first place? If you feel you are unimportant, you are in the wrong room, man!
Instead, think like this: I'm important, and what I say matters to them, and that's why they should give me ten minutes of their attention. I'm going to practice, give them my best shot, and get the best appreciation.
There is a difference between admitting a mistake and learning from it and feeling unimportant. And there is a difference between not taking life too seriously and feeling unimportant. The appropriate mindset should be that I shouldn't stress myself out because they might have other things on their minds, but this doesn't eliminate the fact that I should also do my best to make them give me their attention.
Just imagine an entrepreneur standing before ten investors and thinking their ideas or products are unimportant, or a salesperson thinking their company isn't important.
I really don't know how people here could agree with such a statement. People don't achieve results in life because they don't give importance to what they do or say! Period.
Okay, back to normal me. I'm sure you will take this note as a tough love message. You are a brilliant, smart man. Have confidence in yourself and always give life your best shot. How people behave toward it is up to them.
Best!