So, to compare 100 IQ now with 100 IQ 50 years ago is hard, since you're not using the same test anymore.
There's an effect called the Flynn Effect which is essentially an inflation of IQ, so the tests are changed every few years so that it keeps the same distribution (so that the averagely intelligent human would score 100)
https://en.wikipedia.org/wiki/Flynn_effect
In fact, you can't always compare the IQ tests of 2 humans alive, because the given score is comparing you to the other people of your age, not to the global population. So if you compare the IQ of a kid and middle aged man, it doesn't mean that one is more smart than the other in an absolute way (it's more a theoretical potential)
The average IQ of the people then would be 100, and the average IQ of people now would also be 100, even though there was a huge difference in intelligence. This is because 100 is defined as being the average rather than being an absolute measure.