Should I set up a business for my ZUS and Taxes as someone who earns money online in Poland (YouTube)?

So, long story short, I'm in my early 20s. I've moved to Poland not too long ago. I have Polish citizenship and a Dowod Osobisty, and I'm in quite a unique situation.

I live with my parents currently (so was lucky enough to not have to pay rent until recently), and am unemployed, but recently a hobby of mine has started bringing in some income. I make YouTube videos, and each month Google sends me ad revenue earned on those videos. Some months this could be as little as 500zl, other months this could be as much as 4000zl+ - for example last month I earned about 500zl, and this month about 3300zl.

Now I know that the tax threshold in Poland is 3091zl+ so I obviously have to pay taxes on this income. I assume I also have to pay ZUS.

I heard that if you're "Self-employed" in Poland you pay 18% taxes (up to earnings of ~85,000/year) and around 1000zl a month in ZUS. The problem with this being that my income is so variable - some months I could easily afford to pay 1000 in ZUS, but other months I wouldn't have enough. While overall yearly I don't think I would have a problem paying it - I would still rather pay a percentage if I can.

Is this true that I have to pay a fixed rate as a self-employed person or can I pay ZUS as a percentage of my earnings rather than a fixed rate?

Or, if I can't - would I be able to pay a percentage as ZUS if I were to register some form of company? What would be the best way for me to go about this? Do you have any additional advice?

Thanks in advance! (PS other than being about as clueless as can be about the forms and everything else I have to fill in here, I'm loving it here in Poland!)

You might be able to simply declare the income on the PIT, but I'd get an interpretation from the tax office confirming that they don't consider you as self employed in this case.

Failing that, why not run the income through AIP?
inkubatory.pl

As self employed you will only have to pay a low amount of ZUS for the first couple of years - mine comes in at less than 500 PLN per month. You can also opt for a flat rate of income tax at 19% irrespective of how much you earn (which if you are going to earn significantly more than 85k is definitely worth considering).