What, exactly? Which current startups/tech companies are doing something meaningful? I know a few that are not marketplace(Uber)/ads(Google)/finance(Goldman) companies, but there are not many.
There's a few that provide interesting and new ways to connect with and donate to charities (I forgot their names, but you must've seen at least a couple pass by the frontpage).
There was one developing a robot spoon with stabilizing anti-vibrations for people with Parkinson's. I remember the look on the faces of elderly people in the video, as they could finally again bring peas to their mouths without spilling everything. That was genuine, they didn't need that "I appear in all the startup videos" guy or hire actors.
There's a bunch of startups working to bring encryption and other privacy-enhancing tools to the masses.
These guys providing mobile laundromat service for the homeless. Though I dunno if they were making any profits with that.
A major contribution by tech industry is how it fundamentally transform the way we live, work and interact, in a mostly positive way towards higher efficiency. The effect is everywhere. I don't think you can find many tech companies which are not contributing something to this landscape. Are some of them possibly "more trivial" than others in a perspective? Might be. But it doesn't change the fact that they are having positive impacts on the world.
Like what? If you're learning a new technology, and you also happen to have a great helpful idea that you want to implement, that's fine, but usually you just want to implement something, so you pick up an idea and roll with it even if it doesn't benefit mankind.
I think people overestimate the number of useful project ideas floating around which don't require unusual expertise. Some "starter projects" might benefit mankind, but certainly they can't be expected to do so.
(I speak as one who has tremendous respect for the good that cat pictures have done for the world.)