Scratchapixel: Computer Graphics Programming from Scratch

Meanwhile a teenager could easily get an intuitive grasp of 3D graphics if you just explained how translation is nothing besides addition, and that to rotate, you just use good old trig functions to generate rotated basis vectors along which to plot your vertices (really easy to show with images and animations too). And that magic perspective, to make things get smaller as they get further from the camera, is just one divide by the depth away... yes, all very basic arithmetic. And no need for magic such as homogeneous coordinates. They're just a convenience for when you do things a certain way.

You don't need to go to college or even high school for 3D rasterization. But most if not all texts pretty much want to assume such a background?

Actually, I'm quite tempted to try write such a tutorial for the 12-year-old me. Too bad I can't travel back in time to see if I'd actually understand it (but I have a strong feeling I could come up with something good enough). Yeah, the lack of approachable material was very frustrating for me back then. In the end I wrote a very primitive renderer (with plenty of trigonometry per vertex) which was way too slow and complicated to be useful. Because I didn't realize how simple the problem actually is.

The reason I know those things now is because I wasn't forced to learn them then. Detail comes after engagement.

You should do it! I agree and think that making 3D approachable is possible, and that most tutorials fail to make it easier than already available materials. I'm not sure it's easy to do, but if you succeed then people will benefit and if it turns out to be hard, you'll have developed a stronger appreciation for the problem and/or the motivation to solve it.