hi, im also a web dev in my company.
there are some games made in pure html+css+js and a backend behind. I love this kind of architecture because you can change client (other interface, better graphics) and game still work.
btw for many advances gendres of games your life will be a lot better using an engine (unity, unreal, rpgmaker).
Some smaller ideas could be done with only libraries (phaser, aframe, ...). More easy than a full engine but need to know what you are doing.
IA is a powerfull tool today but also need to know what IA is doing, or your proyect will be hard to add features in future.
Finally, if you are starting, dont worry about licenses, or legal stuff (im from latam :P). Your game will not generate a lot of money so dont worry about that. Is better practice with a lot of external solutions to have an idea about how do stuff.
An example is https://teamwood.itch.io/super-auto-pets
Very know game where players "create" a formations and send it to server. The server do a match with another formations sended by other players in the past and return to player the played match. Is like a multiplayer in real time but opponent in no real time. I think many auto-battles games are like that.
You dont need an engine to do that, only html+css+js+backend/database
im also doing a game now with the same idea using free database and phpserver services.
Finally 2, like dream say, start small. Maybe only do a mechanic and play with it. Many people waste a lot of time doing all levels and art and dialogues and "visual stuff" but later they can't spend three days making the character jump and the proyect never end.