Troubleshoot / Diagnostic help?

[RckyMntnKng]

Gents, wondering if you could provide some ideas or hints.
Here are the events in chronological order

1. Start Jimmy, drive 30 miles. No Probs
2. 1 hr later get in, turns over slowly and wont start
3. Take battery, have it checked (its bad) and get new battery
4. Jimmy starts great, but sits for about a month
5. Start Jimmy (no prob) , drive about 20 mins, park...wont start or even click over
6. Get a Jump, drive it all the way home on dead battery (Alternator must be fine?)
7. Find that the red wire on the back of the Alt has corroded Off completely (Ahah!). Replace connection...This should charge the new Battery now.
8. Jump start Jimmy, drive all around and let it idle so the battery can charge.
Turn off....and then nothing, not even a click.
9. Jump it again, drive a long ways, let it idle etc etc....no starty.

My thoughts at this point:
1. Alt seems good because I can drive it as long as I want, once it is jumped.
2. Possibly got a defective new battery that wont charge?
3. Alt isnt charging battery but is sending power to the spark
4. Voltage regulator or ignition switch? doesnt seem likely if I can run it after a jump.

Im stumped guys, what am I over looking?

Here is another question:
2 red wires come off the battery-one goes to starter, one heads back toward Alternator etc. That second wire hits a terminal and splits off into 2 more hot wires....one is fused and the other is not. I assume the inline fused wire is for the radio or lights or what? That red larger gauge wire hits the Alt.