This is my area of expertise (relatively speaking). RE2 did have some sort of colored map which defined when the character was behind/infront of something - I remember seeing one a while ago, if I find it I’ll edit this post with it. That was the playstation version which didn’t have depth, the N64 version did have and use a depth buffer. The playstations method made a decision based on the entire object - all of the character was infront of something, or none of it was.
Since you said you are a beginner, the easiest way I found to do it was to whack my background image on the screen, and have your model walking around on top. In order to deal with the depth issue you can use a low poly 3d model of the scene, the material of which you set ColorWrite to false so it hides what’s behind it but never draws on top of your background. If you want to, later you can add shadows cast by your player onto this model too. This approach starts to fail if you have a large number of small details, like a wire fence.
As for the camera… I just lined it up in blender then got the camera roation from blender into JME. Depends if you’re making your own backgrounds or getting them from somewhere else. If you happened to be wanting to actually use RE2 data I have a script for blender that extracts camera data and collision shapes from the games invididual .rtd files themselves.
You can go other routes and get do some nice tricks but it gets very complicated that way. If you were making the backgrounds yourself you could render the depth and use it in a post filter. I did this with normals to get screen space reflections.
I ended up applying my background image in a post filter… just depends on what result you’re looking for.