i really like that you want to make your own original stuff and not rely on AI
For the game engine it depends on what you want. if you want a character to move around in rpg style (like my games asylum and captured by dark elves) then rpg maker is the easiest option. rpg maker has a very helpful community on forums.rpgmakerweb.com and there are a lot of tutorials out there, it is very easy to learn
If however you want to focus on presenting your art and make it more point and click (like femdom city and shadow over blackmore) renpy is the better option. it requires a bit of coding but it is actually very easy once you get into it. there are some good tutorials on youtube and renpy has the lemmasoft forums as well as a helpful discord channel.
Now, the artwork...that is more difficult. There are not many tutorials. For the 3d render animation engines I used Poser Pro 11 for 6 years and now using daz3d for 3 years and I still would say I am a beginner. The most important thing is to just start. Don't worry about it much, just download and install daz and play around with it. focus on older models like genesis 3 & 8, pick up some free or cheap assets and start learning by doing. There are not many tutorials out there, but googling a specific problem usually points you in the right direction. at least that is how I learned it ;)
Another tip is to focus on a small location for the first game and narrow the story down. Like you mentioned: a prison. or an apartment, a hospital etc. that way you can focus your attention on a few events and characters. This makes it easier to start and finish your game!
hope it helps,
good luck making your dream game :)