Why is my shift register circuit not working?
Your code is full of errors. Your pin index's are wrong and clock, latch and data pins are all inputs. With inputs defined as outputs you get no useful results.

According to the datasheet, you should just set pin 9 'high' so it always parallel loads, then use clock to shift data out. Not sure why you have an inner loop for the latch/load pin.

NOTE: I would use an 8 section DIP switch to input whatever pattern you want, then have the MPU toggle the control pin and clock pin to shift the data out at Q8, which you have flagged as 'IN_DATA', although I do not see that on the connector.

Slow down and pay attention to details, double and triple check your work, or software will drive you crazy.