Yes, could be something else. Ignition switch, starter relay, broken wire, etc. In order to diagnose the car needs to be in a no start state while you check voltage along the circuit, that way you can determine where the issue is. Lots of good YouTube videos on how to do that. If you’ve already done the alternator and battery I’d start with checking the chassis ground and starter relay, assuming your battery connections are good. If it’s only happening intermittently, well good luck. Just went through this with a vehicle.