What transmission do you have?
If manual trans the clutch switch might be disconnected or bad, it's on the clutch master cylinder to pedal push rod(inside under the dashboard).
The clutch pedal must be in all the way for starter motor to work, that's what the switch detects.
If automatic trans there is a Neutral safety switch(NSS) that could be disconnected or bad.
Transmission shifter must be in Park or Neutral for starter motor to work, this switch is in the transmission just above the shift linkage, it can be tested and adjusted or replace without dropping the trans, there are also 2 connectors on the wires that can get corroded.
The connector on the switch itself and usually one at the top of the bell housing where it goes into the main wiring harness.
If you want to test if this switch might be the problem, MAKE SURE TRANSMISSION IS IN PARK OR NEUTRAL!!!!!!!
On the starter solenoid you will see one, or two, smaller posts, you want the post labelled "S", it will usually have a small red wire connected to it, that wire activates the solenoid when it has 12v.
If it has a push on connector remove it, if its a nut leave it.
Use a jumper wire from the "+" battery terminal to this post, make sure key is OFF or in your pocket
MAKE SURE TRANSMISSION IS IN PARK OR NEUTRAL!!!!!!!
Starter should crank when you touch 12v to the post, if other cables are good
The wire on the "S" post gets 12v from the key being in the start position, but that 12v passes thru the clutch switch or NSS switch to get to the solenoid, so you are bypassing the key switch and clutch/NSS switch on this test.
But if key switch was the issue then you probably wouldn't hear any "clicks", the click could be the EEC relay and Fuel pump relay which both come on(click) when key is first turned on.