Can I build muscle lifting light weights with higher reps?
Here is my view regarding building muscle. It is a fact that when resistance training improvement can only occur by adding resistance.
Let's say your genetic limited squat is 300 kg and you can only 250 for 1 rep. You can then choose to do say 220 for 4 reps or 150 for 15 reps until failure (these numbers are just theoretical).
For the low rep routine as you progress you will finally reach 300 BUT at this weight YOU CAN ONLY do 1 rep because that is the final limit of your strength.
The same goes for the high rep routine and as you approach your max the reps you can actually do will be reduced no matter how hard you try until you are at 300 and able to do just 1 rep.
So both ways lead to the same FINAL result. The only conclusion here is that there is no difference EXCEPT the time taken to reach your max. The high rep routine takes longer to achieve the same result, that's all.