Definitely this . I struggled a bit when first playing GG, but over time I was able to get most of the basics down with more practice and learning where I've struggled (and still struggle in some places to this day) and get better against other players. I myself am able to get some good combos going and get some good wins against other players, but where I struggle is trying to mixup and utilize all moves of the character I'm playing as when fighting against other players, and using roman cancels properly either during my combos or to throw off the other player and use it to my advantage.
It also helps to have a character you're interested and motivated to play as, as it allows you to get more invested in what their strengths and weaknesses are, both in general and their matchups against other characters, and motivates you to keep practicing. It seems like you have one already, so if you're interested in playing Ky, practice as much as you can with him and look up some vids of his combos and basics too. One tip that could help is going into training mode fighting against the same character your playing as, and set him to com to see what kind of combos they do to possibly utilize as well.
Nothing wrong with trying out other characters and seeing if a different character is right for you or at least be a sub, but be aware that even though there are general mechanics for all characters, almost every character in the game plays differently from each other in GG compared to other fighting games, so I'd recommend getting one character's basics and combos down before having a sub. Doesn't help in my case though that I'm trying to learn and main a character that's exclusive to Revelator and having very limited access to the version's demo until the game's release hasn't give me much time to get better with said character, but thanks to watching vids of the character and having a basic understanding of the game's mechanics, I'm doing better than I was expecting to.
Once you learn where you stand and where you struggle both in game, try to focus on where you struggle and work to overcome them. Experience against other players can definitely help in this regard.
Lastly, training and experience against other players (local preferably if you have the chance to do so, but online can help as well) is one of the best ways to get better at the game overall. The time it takes to do so varies on the person and the struggle to get better can get quite frustrating at times, but persevere and over time, you'll notice your muscle memory and yourself in general getting better at the game, and you'll be pulling off awesome combos, have intense matches, and winning against other players before you know it.
Hope this helps a bit.
It's like Capcom's deliberately trying to get people to stop playing and supporting SFV. You'd think they would learn from the bad reception they got the last time they tried to hype up an announcement after a tournament and ended up being sub-par to say the least (back in March with Alex they teased everyone with the possible Alex trailer, but ended up being nothing but RAAAAAAAAAASHIIIIIIDOOOOOOO playing in the background. Infiltration was even asking for the trailer).