You may be familiar with the proverb:
When in Rome, do as the Romans do.
If the expected behavior is to shout loudly and force your way to the front of the queue then either adapt to the local custom or find yourself eternally at the back -- or go somewhere else. Sure, you might retain your dignity, but how much is your time worth to you?
But I suspect there's an underlying question, something like:
If I'm not a naturally assertive person, how can I learn to be assertive in situations that require it?
There's another trite aphorism to cover this situation:
Fake it 'til you make it.
Imagine you're an actor onstage, and your character is an assertive narcissist who feels they should be first in everything, and who cares nothing for social niceties. How would that character act? What would that character say?
Would they be worried about stepping on other people's toes (metaphorically speaking)? No. Would they care about making all the other people wait for them? Not in the slightest.
Be that person -- wear that jacket -- but only until you accomplish what you need to. Then take it off and be "yourself" again. Eventually you may find you don't need to pretend, that you can be assertive when you need to be, and polite the rest of the time.
If you're worried that other people will think you are a "bad person", well ... the fact that you even ask that question probably guarantees that won't happen. Plus, unless you're especially aggressive or annoying, you'll just be another forgettable face in the crowd.
On the other hand, if you feel that manners and dignity are more important, than you have a decision to make, whether you choose to regularly attend venues you consider undignified. This might mean giving up some of your social connections, but that's why we each have to make our own choices about what we value.
On a side note: The situation you describe is much like what I experienced when I went to mainland China. There, people most often swarms rather than queue, and the only way to get to the front is through steady physical force -- even in places like airports and train stations, where (if for no reason other than safety) you'd expect more organization.
I would have missed my flight if I had held my usual reserve, but again, as the Romans do, I let go of my preconceptions about what is "polite" behavior and shoved my way through.