1 - There is no magic pill in life. If you want to get physically stronger, leaner, or build endurance, you have to spend the time training your body. The same goes with learning. If you want to get smarter/know more, you have to spend the time studying.
2 - As a whole, we are a species who continues to learn. Everyday, we make new discoveries that challenge what we thought we knew about nature, physics, medicine, etc...but also, we evolve as well and change things as we grow in our humanity. For example, old laws may be removed that no longer apply today, or new laws may be created because something new exists in our world that didn't before.
We are a forever changing species. For me personally, my goal is not to "know everything" but rather accept that I don't know everything but be open and curious to learning as much as I can. And remember, there is a difference between being "smart" and being "wise". For example: A smart person knows that tomatoes are a fruit, but a wise person knows that you don't put tomatoes in fruit salad :)