Possible Code Issue?

Your picture shows the servos plugged into servo connectors 12 to 15

Your code sends commands to servos 0 to 4

    Serial.println("Moving servos to 0 degrees...");
    for (int i = 0; i < 5; i++)
    {
        pwm.setPWM(i, 0, angleToPulse(0));
        delay(500);
    }

Can you see a problem ?