Yes, we really went there. There's zero legitimate doubt. If nothing else, consider: the Soviets were locked in a massive propaganda war with the US over the respective countries' space achievements, with the Soviets spending vast resources to show that their ideology was superior by showing what they could achieve in space. They had no trouble tracking American activity in space. If the moon landings had been fake, wouldn't the Soviets have brought their receipts and utterly humiliated their rivals?

We haven't gone again since because there's not much point to it. The US spent an amount of money equivalent to about 10 Manhattan Projects to ultimately put a dozen people on the moon for a cumulative total of somewhat less than one person-month. There was no military utility to it, no commercial benefit, just some science and exploration. Once you've done that a few times, what's the impetus to continue?

The technology was so bleeding-edge that each mission required a huge amount of bespoke manufacturing that got thrown away after a single use, and massive teams of people to run everything, such that each individual mission still cost billions of inflation-adjusted dollars. The American public's stomach for spending such vast sums of money just didn't last. Imagine if you needed to build and throw away an entire Airbus A380 to reach the summit of Mt. Everest. Maybe it would have been summited a few times to show it could be done, but we probably wouldn't keep doing it.