You've checked the microswitch and the key switch? Usually one of those two are the culprit. Somehow your solenoid is getting engaged, and if a wire isn't jumping from post to post, then it's definetly the key switch or the pedal switch.
No, not if it is not defective. If the ignition switch is defective then that is all you need to replace.
When you determine that it is defective.
Defective ignition switch or tumbler assembly.
Defective ignition switch.
Have you checked If copper plate main fusible link in underhood ok ? Defective ignition switch is another posibility.
No, if it starts on its own without you turning the ignition switch then the ignition switch is defective.
The ignition switch is defective.
Defective ignition switch.
Defective ignition switch.
Engine seized? Loose or corroded battery terminals? Flat spot on starter? Defective starter solenoid? Defective neutral or clutch safety switch? Defective ignition switch?
Defective ignition switch.
Defective ignition switch, or bad starter.