e isn't just a number. (nor is it just a letter) It has a real physical meaning. We can think of it as a unit of continuous growth, and use it to scale all other growth.

Credit for images

John Napier https://en.wikipedia.org/wiki/File:Jo...
Jacob Bernoulli https://en.wikipedia.org/wiki/File:Ja...
Leonhard Euler https://en.wikipedia.org/wiki/File:Le...

bank https://pixabay.com/illustrations/bui...
gun https://pixabay.com/vectors/gunrifle...
gun2 https://pixabay.com/vectors/pistolgu...
calculator https://pixabay.com/vectors/mathemati...