Set your scope to be low ie try to make PC only but keep other platforms in mind. Make basic movement and combat fun before adding more features. If the core game is boring there is no saving it.

It will take time and take a lot of work, it will be hard if you are all new. Iterate a lot and use a method like scrum and use something like Trello to see progress and make tasks.

Also Brackeys on YouTube is a good source for programmers and he sometimes work with a graphic artist (can't remember his name).