GOG is probably your best option out of many....games were nowhere near as complicated in the 90s and early 2000s (in general) and they literally specialize in....Good Old Games.

Sure there are complicated older games too (and they still carry modern games) but you're going to have better luck with older games.

Here's a classic recommendation from GOG - Epic Pinball. Dead simple, great retro feel, fantastic music.

Only way to get better at anything is to do more of it. One of the ways I got good at a lot of genres was playing games with cheats and trainers. It took away the threat of dying and let me just learn how to move around and work the controls as a kid. A lot of modern games don’t let you do this, but if you go back to the 2000s, almost all those games had cheats or trainers and are far simpler to play. And GoG is just the place for those old games.