Another good channel is Godoteneers. He has hour long viseos usually, but he goes through the concepts in ways that a beginner might approach them and then iterate on them while explaining why one way doesn't work or why you might want to use another.
But all in all, most tutorials aren't going to teach you much for actual development. They're too laser focused. I've never used any of the udemy or similar courses, but I often find quite a few books that have taught me more generalized dev knowledge.
- The Art of Game Design: A Book of Lenses by Jesse Schell
- The Ultimate Guide to Video Game Writing and Design by Flint Dille and John Zuur Platten
- Fundamentals of Game Design by Ernest Adams
- Games, Design and Play: A detailed approach to iterative game design by Colleen Macklin and John Sharp
These have taught me quite a bit.