Your project sounds really complex.
I recommend you make a few microgames and then minigames first until you are decent at making minigames, and then you make one or two mid-sized games.
Only then do i see this ambitious game becoming successful, because without practice it's too much to handle even with the help of other artists.
Also you need a way to have a conversation about the game and the work with the artist. If you want to stay within Godot forums, DMs might be a good way.
Also not many people would help with any game project if they don't know if it's possible for the end result to be a good game.
If you show some cool concept sketches (even better if you also show a prototype), and advertise your previous games by stating that "I made <this game> and <that game>" somewhere in the post, you'll be Much more credible and then people might want to work with you much more likely.
And because people normally don't work with other people for free you might also need to accept that you'll have to pay the artist. And make sure to ask to see the artist's previous work before deciding if you want this artist for your game.
And you might also want to practice working with another artist in making one or more of the minigames you make before the big project.
That's a lot of stuff, and i might've missed a lot of stuff, and i know this comment is really harsh, but hopefully this helps to success. I wish everyone good luck.
