The signal goes through a 22 Ohm resistor either to match the input impedance of the ADC or to minimize the current sink at the ADC input.
But I think the 22 Ohm might be useless at all, ADC inputs are high impedance inputs to avoid loading the signal source.
The capacitors are of no use at all, it will add a delay on the change of the analog signal because it will store the voltage level therefore not getting the actual reading present.
Current limiting is not really an issue on ADC's, the best to do is to follow the maximum voltage input allowed on the ADC pin, if you think your input exceeds or is less than the requirement, you can always use a signal conditioner IC to match the said requirements.
Glen