Should we learn bitcoin or not?
Ideally, we should but I don't expect everyone to understand or try to learn how bitcoin transaction works.
It's the same situation with banks, I seriously don't think the masses even know how their money is being transferred or used. They just give their money then wait.
Should we promote simplicity and avoid complexity?
Promote simplicity and give them the option to learn about the complexity if they so desire. We can teach them the basic features such as borderless payment and censorship resistant.
Many of today's wallets are trying to provide convenience to the masses. A lot of them works similarly with other mobile apps that offers financial services like banks. Sending and receiving was made simple too with the integration of QR codes. Default fees are set and advance users can customize it in some wallets.
Can bitcoin continue to exist if majority of people don't want to be taught about importance of bitcoin and ideas behind it?
Unless we have AI who can learn to operate mining rigs and nodes, no.