Good work
Yes, the high AMPS needed by starter motor, 60-75amps has no other equivalent in a vehicle, all the lights can work and radio and heater fan, all at the same time(20amps), and a battery cable still may not be able to pass the 60-75 amps needed by starter motor, so "click, click, click"
After engine has been running for at least 10min, leave it idling and test battery voltage
Should see 13.5-13.8volts now at the battery, if over 14volts then battery is dying, its"telling" alternator it needs more volts
Turn off the engine and wait 4 to 10 hours, overnight
Test battery BEFORE startup
12.8v to 12.3v is acceptable
12.2v or under means get a new battery sooner than later