It was incredibly easy to get men to the moon and even easier to bring them back.
Well no, it wasn't. The first American in space was in 1961, the first man on the moon was 1969. That's 8 years of work with a LOT of money thrown at it, as I showed above it was around 4.5% of the budget of the the entire country at its peak.
Did nasa ever do a trial run
Yes. They did
loads of trial runs.
It was Apollo 11 which went to the moon. Before Apollo there were the Gemini and Mercury programmes.
The other Apollo missions were used to practice all kinds of things needed to get to the moon and yes, including rendezvous.
A whole list here:
https://en.wikipedia.org/wiki/List_of_Apollo_missions#Unmanned_test_missionsLoads of unmanned missions to test the rocket.
Apollo 8 went to the moon.
Apollo 9 tested rendezvous and docking
Apollo 10 tested the same thing but this time at the moon - the LM descended to 8.4 miles from the surface before coming back and docking.
Apollo 11 landed.
So yes, you can see in that list that in incremental stages they tested every thing they could practically test.
On earth they spent hours and hours in simulators testing every conceivable scenario and malfunction.
They spent time practising landing in a device which had rockets which fired to make the craft act as though it was in one 6th gravity. Armstrong famously crashed one, ejecting not long before he did so.
So yes. They did lots of trial runs. It wasn't easy.
You can't change physical laws to enable rocket engines to produce thrust in a vacuum
You don't have to change any physical laws.
https://www.livescience.com/34475-how-do-space-rockets-work-without-air.htmlSo why is it so hard to put man above earth orbit now?
It was always hard. And I posted a link above showing the effect of the Apollo missions on the astronauts.
A combination of budget cuts compared with the 1960s, a lack of political will to go back to the moon and a lack of public interest meant the focus has been on other things like unmanned probes, the Shuttle programme and building the ISS. The focus seems to be switching back to the moon again and I'd be very excited if they did go back as there hasn't been a manned mission in my lifetime, and I'm not that young.
Quite honestly, your arguments are a mix of incredulity and ignorance. Read "A Man On The Moon" by Andrew Chaikin if you want to learn more about the Apollo missions.