Financial literacy is something that unfortunately, in my work, I've seen a lot of people miss out on, with significant consequences. Admittedly, it's something that isn't taught much in schools, but quite often, parents miss providing guidance on it as well, and here, I think they may be wishing to impart some prudence on your spending, as others have noted.
I presume (and correct me if I'm wrong) by your wording that you are likely paying little or no rent / room and board. If so, this is a really financially advantageous situation, since you end up skipping what for many is their largest expense, and one that in some places, can take up more than half of one's take home pay. What this results in is a situation where although your income might be relatively modest, because you have little fixed expenses, you end up having a fair amount of disposable income. This can lead to someone spending more than is prudent on "fun" things (whether that be travel, dining out, buying collectibles, or commissioning art, just to name some examples). But what if circumstances suddenly change? Even if a parent is open to supporting you on an open-ended basis, sometimes things happen.
So consider this - if for whatever reason you suddenly find yourself no longer able to stay with a parent, do you have an emergency fund that would allow you to survive on your own for at least several months? If not, then that's probably your first priority. While we don't want to think of the worse, we should always be planning and being as prepared as we can. I've seen far too many cases of lives being completely destroyed as someone was unable to handle an unexpected outlay of money, which then leads to a bunch of other compounding issues (like moving away to a place they can afford, but losing their job and support network).
Once you have an emergency fund, then you have more flexibility - you may wish to put aside funds for various things - long term savings (e.g. retirement, housing, education), as well as some medium and short term things (travel, something you want to get), and whatever you have left, that's your discretionary spending, and you can truly feel free to spend that on whatever you'd like, knowing that you've got other things covered. You may have noticed I put retirement in there. I know it's a long ways out, but the magic of compounding means that the earlier one starts, the relatively less they need to put in.
You mentioned art school - have you given thought to potential ones you may wish to attend, their costs and requirements, and potential outcomes (e.g. where their graduates are now)? That might be something to spend some time on exploring. Not a lot of artists end up "making it" solely from their art - many also have a full time or part time "day job" to provide financial stability - and that's perfectly fine, but then you'll want to consider what jobs may allow you to do both. (e.g. a job that involves working weekends might mean you're not able to attend art shows)
