The fact that kids barely older than me in the 80s were cranking out stuff that used the C64 to its limits blows my mind. The demoscene is intensely inspiring, if really impenetrable to an outsider.

The best way to penetrate it is to just write a demo! It's fairly certain that it will be terrible, but the point is you tried and you will improve. Hopefully you'll get some pats on the back along the way, inviting you to try again with a second demo, and so it begins...

A demo seems like a seriously high hurdle. Maybe a 4K intro.

Some years back, Farbrausch released a "demo creation kit" of sorts, called Werkkzeug. It's still around, and it's a great way to dip your toes into the expressive end of things without having to hand-hack a bunch of assembler code.

Find out if you like creating things like that, and then level-up the skills as necessary to make it completely your own.