There are both circuit breakers and fuses used on this vintage of Mopar vehicles. Fuses live under the instrument panel, circuit breakers live behind the driver's side kick panel. As previous people mentioned, it depends on the circuit you're working on if it's protected by a fuse or circuit breaker. It's my understanding that when you're dealing with circuits that uses coils (like motors) they're protected with circuit breakers. This is because coils by nature have relatively large inrush currents when you first activate them, which would fry a fuse overtime, even at normal loads and use. Circuit breakers avoid this problem, while still protecting the circuit.
In this particular case, the spade connector came detached from the circuit breaker. Even though the fix might have been easy, there is reason for concern here, as spade connectors are supposed to fit snug and not come loose without applying some force. The fact that it did tells me it is indeed sloppy or loose, and therefore causing electrical resistance where the 2 surfaces mate. Even just a few Ohms of resistance can be a problem here, as we're dealing with large current loads. You could potentially start a fire. Mopar used insulation material behind the kick panels and other areas, and when I tried for sh*ts and giggles to see what holding a lighter would do to this material, the result was sobering. This stuff is actually flammable! So I say get a new spade connector (crimping the old one tight won't do), clean the spade on the circuit breaker, attach the connector to the wire (make sure it fits and is crimped snug) and make sure the spade fits tight on the blade when you connect it.
Last but not least, this wire goes straight to the master window switch in the driver's side door. The connectors that connects these wires to the switch unit are usually worn, corroded and the terminals that connect to the pegs on the switch unit can be sloppy, loose or separated altogether. If the power wire coming from the circuit breaker has a loose terminal at the switch, you'll have intermittent or dead power windows at best, and/or a 30A power wire flopping in the breeze, less than an inch from large grounded areas (sheet metal). I'm not sure if someone makes new connectors for these switches?
Hope it helps, sorry for long winded answer.