Trying to learn all the functions; struggling to understand drills.

Maybe I'm just missing something. But when I practice drills, a lot of times I'll mess up, but unlike puzzles, there's no option to show solution. I have game analysis and key moments, but those don't seem to help much because I can't see what the computer thinks I should have done beyond that singular move. A lot of times I'll see it say I blundered, for example, but can't quite grasp why. So am I missing something? Honestly I'd love if the drills had a solution button that showed you the optimal way to play it out. Because for the life of me I can't figure some of these things out

There is no exact right answer. The situations are unbalanced. You have to make a plan and try to carry it out. 

For example, I tried the position where I was white, all pawns and kings were in their normal starting position and I also had a rook on h1.

Have you tried that one? It took me 40 moves.

I think I did okay but I know that I wasted  a bunch of moves.

Computers still can't figure out the exact series of moves in such a situation.

Initially, I thought to just push the g and h pawns and force a trade of pawns to open a file. After 3 moves, it became clear that plan wouldn't work and that I still needed to control the center, bring up my king, etc.

I am curious now to try it again. I would guess that it can be completed in less than 30 moves by someone who could come up with a better plan than I did and didn't waste moves. 

I did it again and took 31 moves.

I don't know what the minimum would be against the drill computer's resistance.  

There is no point in trying to get a list of moves to memorize. There are too many moving parts. You have to be able to look at the position and figure out a plan.

Okay, and if I can't figure something out, then what? Not everyone is able to work their way through a puzzle with trial and error. I personally learn better by example. Yes, I understand board states aren't ever going to be the exact same, so you'll have to adapt. But several drills I've gotten stuck on and said "Welp, i've been doing this for a half hour, I'm frustrated, and the program's not helpful, so I guess I'll never learn how it's done." Even just showing an example would be nice for visual learners like me. Drills are supposed to help you learn, but if you're stuck, can't figure it out, and it won't show you, what's the point?

I think drills are intended to help you practice what you've already learned. They aren't necessarily supposed to teach you the basics. You may be misunderstanding them. For example, the end game drills are confusing if you haven't learned the basics of king and pawn end games, opposition, out flanking, shepherding and a number of other end game skills that are taught in the tutorials section. Consider working through the tutorials, getting more playing and studying experience then revisit the drills.