Maybe you don't realize how important humans in the loop are. Astronauts during the Apollo mission could do way more in a much shorter period of time than, say, Mars rovers, even 50 years after.

People can take initiatives on a completely unknown environment way better than our best computers can, including fixing things. That's a reason manned space stations are so useful, you can launch an experiment up there and know than there are smart people who will make things work even if you forgot some minor details. It is even more important the further you go, as latency increases.

In addition, manned space exploration tells us valuable information about ourselves. About our bodies, our mind. It may lead to valuable medical discoveries. And of course, at some point we will want to go there in person, from long term goals like space colonization to simple curiosity, and these are the things we need to know.

And I don't think manned space exploration held back anything. Manned exploration is inspiring, and Apollo was an important political move, it means lots of funding. Pictures of outer space clearly don't have the same impact. It is easy to see, for the decades where no one considered manned space exploration, not much happened compared to what happened in the 70s, including on the unmanned side, simply because of shrinking budgets due to the lack of interest. Yes, we did stuff, but Voyager, Venera, Hubble, Pioneer, etc... all in the 60s and 70s.