@smurfsareblue
I’ve always struggled with this for books written 100+ years ago. I suggest looking past the problematic parts like the ones you mentioned and looking at all the things it does right – the ideas of the revolution are focused on the poor not wanting to be oppressed by an overmighty government – a very relatable theme. The characters a lot of the time are fighting for the rights of those less fortunate.
My most recent English project was actually on feminism in Les Mis and my conclusion was yes, it’s pretty sexist in the details and some of the stuff they say, but look at how women are used to advance the novel (fantine isn’t blamed for her fall, but instead the guy who abandoned her is, rightfully so).
If all else fails, be glad that times have changed and that you’re clearly a good person for being able to recognise the problematic parts – not everyone is as well educated/sensible.
The good thing is that the modern fandom of Les Mis is very very liberal and diverse, and so even whilst the book is problematic, the modern versions are the opposite.
Hope this helped? Happy reading x