I just started game development, not sure I'm coding right

I mean my code works Most the time at least...

But other than that, whenever I need a solution to fix or make something I turn to variables.

Nearly over half my code is variables Inventory system? Variables Movement? Variables Currency? Variables

Every problem has an answer. Variables

It just feels too simple using variables for EVERYTHING Is there a more effective way to do things? Is coding JUST variables? I mean if so I'm not complaining

I feel I'm missing a big chunk of information because it all seems to easy to use variables for everything. It works for now but does it effect my game long term?