FWIW my school introduced e as a base of natural logarithms with “it’s a special number, don’t worry about it. Good thing: your calculator knows them, too” and for a while we all thought that “natural” somehow related to being calculator-friendly.
Then later we got introduction to e in terms of derivatives and complex numbers. However, compound interest was never used for exploration, and I only got introduced to the it’s connection to e and as an explanation for what e is late in my thirties.
https://www.3blue1brown.com/lessons/eulers-number
As suggested by the OP, it approaches the problem from the angle of showing that e^x is the only function that is its own derivative.
There is also a follow up explainer giving intuition for e^ix as being about modeling rotations.
https://www.3blue1brown.com/lessons/eulers-formula-dynamical...