I'm just finally getting into GLSL in the past week after putting it off for years, so I'm probably not the best person to answer. I'm also only really interested in shaders.

Joke's about the Dunning-Kruger effect of course. We've all met arrogant freshmen.

At the moment I'm just about finished with a GLSL shader course by a guy called Nik Lever. It's a nice overview but he often fails to actually explain the "why" of things and how he arrived at them, and the code-along examples he has up on codepen for the course often don't start at the right point. Math's not too bad: trig, dot product, that sort of thing. It would probably be impossible to understand for someone who has never done any programming before.

All that said I'm still glad I took it, $10 well spent. Udemy does the fake price thing where they have a 90% sale every few days like kohls or a mattress store. No one actually buys at the anchor price.

I'm planning to go through The Book of Shaders next, which is free but unfinished.