Did we learn anything new and truthful from the inhumane experiments during the holocaust?

Hi there! You might be interested in two past threads, one from this subreddit and the other from /r/AskScience:

As fucked up as it was, did the Nazis actually make any medical or scientific advances by using jews as test subjects, and having the capability to perform experiments on humans?
Did Dr. Mengele actually make any significant contributions to science or medicine with his experiments on Jews in Nazi Concentration Camps?

I strongly suggest you read both answers - they aren't too long - but just as a TLDR

From the first answer:

If memory serves, some experiments did. Questions like "how long can a human be exposed to temperature x" or "how long can a human last without water" were desired by the Nazis to help soldiers, particularly on the Eastern Front. So data gathered from that was actually useful, at least to get a ballpark figure.

But the more horrific experiments were too pseudoscientific and unsystematic to yield any useful data. They didn't answer serious scientific questions, and didn't really produce any data that could be used to answer them if they were. Mostly, they were just desires to torture people in interesting ways, actually break scientific ground.

From the second:

I'm not sure who in WWII Germany generated the data but there is a wealth of design data about the limits of the human body which was instrumental in laying the groundwork for manned spaceflight. Basically it's a set of data that tells you how many G's a person can be expected to survive in addition to temperatures, pressures, gas partial pressures (how much Oxygen and Nitrogen you need etc...), some of which I've been told before came from these experiments in WWII Germany.

It's the sort of data that you'd rather just not have -- that it's not worth suffering over, but begrudgingly you make use of any data available. Particularly when you have no data to start from.