Converting blueprint single player game to multiplayer game.

So, I’ve started making a game in which I want multiple people to be able to fight each other alongside AI. I decided that I should get the base mechanics working first a simple AI, Weapons, Movement, Animations, Models, Ect. I made it single player assuming that it would be easy to then make it multiplayer once I had refinded the concept, however I am now facing quite a few problems in doing so. Firstly Because all the players use the same base character they seem to share a health variable and I am not sure how to solve this furthermore when a player attacks on one screen they can see their attack animation but it cannot be seen on the other players screen.

I’ve tried searching around for answers but haven’t seemed to find much that can help me so far, any help would be greatly appreciated.

Multiplayer requires a lot of thought and understanding of pretty much every concept of game design. So you need to first learn the basics.
Here’ some sources to get you started (In order). AND actually download the content examples and look at the blueprints.

Is the health variable stored in the Level Blueprint or something?
Maybe place it inside each character instance to have unique copy.

Hard to argue against any of that. its pretty much the truth.
About the only exception is local multiplayer split-screen etc.
Epic did a tutorial on this recently, see their YouTube channel.