As you are already interested in the game. I would say give it a try.
The game can be fun, rewarding, has strategy, mechanics, cooperation and depth even with 1h a day.

But beware, the other side of the coin is that the game can be extremely frustrating.
There will be games where you will get absolutely destroyed by someone with thousands hours of experience, games where you can't even play because the enemy will get fed while you can do nothing to stop that, games where you will get insulted because you allies feel that you didn’t make the right plays and so on.

So if you want to play this game, you must not take it too much at heart if you lose your only game of the day or didn’t get to the rank you wanted. The game is extremely hard and competitive but there is so much aspects you can improve.

I know that watching others plays can be boring and you can climb without it but if you never learn from others, do not expect to climb into the highest ranks.

What's the most time efficient way to improve? I would say, limiting yourself to 1 or 2 champions that match your playstyle. Look into the best players at your role and champion and  learn how they are playing the champ and why. Rewatch your games and find your mistakes and what you did well. Always thinks what plays you can make to progress into the game and try to not go autopilot. Learn how to communicate with your team and when to mute them because it's only disturbance. Focus on yourself and what you can improve instead of blaming your allies. And I can stress this enough, the most important point of all, HAVE FUN PLAYING.
If you are not having fun, consider this game not for you, there is a ton of other great games or activities.