I always found this quote deeply inspirational.
What does it mean? Here's my take on it: All the knowledge that came before us and we have "innate" is a great advantage.
The first humans had a great responsibility. There was nothing before them. What they did shaped the future and the identity of the whole specie. Of course, they couldn't know that at the time.
What we do now though is just as important. Since we're living on the shoulder of giants(, we should feel even more responsible not to squander it and contribute to the future somehow. If they could make incredible inventions without all the knowledge that we have today, how we cannot with a basically infinite amount of knowledge.
Is knowledge overload even a thing? I don't think so.
Surely nowadays it is way harder since most of the basic inventions have already been discovered. What someone might not realize is that there is still so much that we don't know (for example about the universe).
It's not that we discover fewer things, we discover way more.
The rate of progress is exponential, but nowadays the steps are smaller.
Why it feels differently
Since you're living it you see new discoveries as incremental improvements, not revolutions. At the same time, you see the past through the lenses of history and don't think about the process behind them.
Looking for interesting areas to explore? YCombinator has a list of areas of interest.