Hey Seth.
I’d just make sure the electrical connections between the battery, solenoid and starter are sound, and the battery is fully charged. If the key switch won’t start it, and your jumping the solenoid won’t either, then it’s almost sure the problem is with the starter. Sometimes the gear that engages the flywheel is made of plastic, and it wears over time, requiring replacement of the gear only, instead of the whole starter. Either way, the starter removal and installation is fairly straight forward and simple (don’t forget to remove the ground from the battery before you start).
Good Luck.