No. Protecting property from looters. Looters who had already spent the past two days destroying innocent people's property and businesses. Conflating protestors and looters is yet another error I keep seeing people make.
And no, jurors can't and shouldn't just "use their common sense". Don't you see what a nightmare this would be for the legal system if jurors just got to go with their feelings? Jurors are tightly constrained in how they adjudicate a case. Great efforts are made to ensure that their subjective feelings don't influence the outcome. Because, and this is important, the legal system is designed to eliminate as much bias as possible when trying a plaintiff. Again, it doesn't always work this way for black people. This is a problem. But it's a different problem.
The jurors can't just arbitrarily decide they didn't like the way Rittenhouse behaved and find him guilty of something he didn't do, or crimes the prosecution didn't charge him with. This is what the people who are actually missing the point keep demanding that they do.