Help Understanding Active Mode Transistors

I am having a hard time understanding why a NPN transistor functions as an amplifier. I will use the following image as a reference:

https://preview.redd.it/tmxde5sgfysc1.png?width=951&format=png&auto=webp&s=8218d7230e220e24835edd228334683fb263e39b

I understand that a very strong current will be formed from the emissor, but I don't understand how this current will be able to pass the depletion region of the colector-base junction. My textbook says that there are no electrons in the base near the depletion region, which I think is contradictory, because for a depletion region to exist, it is necessary to have a acumulation of negative charge in the base. It also says that there is a electric field formed in the colector that encourages the current to pass to the colector. How is that field separate from the depletion region field?

Thank you.