Current sense driver feedback line
For example if ADC sample rate is big enough is there a possibility we capture the 0 in the PWM period, so we get very variable values through the ADC?

Yes. There are several solutions:
First, where is your current measurement shunt? If it is in series with the load, then it will measure current all the time. But if it is in series with one of the MOSFETs, it will only measure when current flows through it, ie when the MOSFET is ON. The rest of the time there will be no current through the shunt so so voltage across it. This can be used to lower dissipation in the shunt.  For example if you make a buck converter with a low duty cycle, you can put the shunt in series with the top FET, which makes shunt dissipation proportional to duty cycle.
If you want the ADC to measure average load current, then you need to put the shunt in series with the load. Otherwise, if the shunt is in series with one of the FETs, you'll measure average current through the FET and not the load. This is a problem if an inductor or inductive load is involved (ie, switching converter, motor, etc). If you use simple PWM in a non-inductive load, then the current in the FET is the same as the current in the load, and it makes no difference where you put the shunt.
Then you need an anti-alias (lowpass) analog filter and set ADC frequency high enough. It's the same as sampling any other signal, frequencies above Fs/2 are folded back in the wrong place, see sampling theory.
If you want instantaneous load current to use in a feedback loop, then the delay introduced by this filtering will be a problem as it will introduce phase lag in your feedback loop. In this case you have to synchronize the ADC sampling time with the PWM. Most microcontrollers with PWM and ADC have hardware for this. When the ADC always samples at the same point of the PWM, usually right after one FET turns ON, then the current ripple won't appear in the ADC results. You'll get instantaneous current.
But you won't get average current. If there is an inductor, current is a sawtooth waveform, so if you always sample on the peak you'll get peak value, etc. And if you use simple PWM on a non-inductive load, to know the average current you have to multiply this instantaneous current value by the duty cycle.