Humans have trouble understanding very large and very small quantities. Stuff over a million, or smaller than 1/1000th is just difficult for us to conceptualize. For example, we tend to think that a billion isn’t that much bigger than a million. But there are 1000 millions in a billion.
Likewise, our understanding of time and how long ago things happened is kind of fuzzy. Here is a great visualization of time. (there are some naughty words in there, beware if you are of timid sensibilities)