oh so I give you a key that everyone can see, but can only be used to encrypt, and I have a different key that no one knows that I can use to decrypt what you return to me and vice versa

How does the recipient device know the encryption key?

I'd assume a new key has to be generated everytime and if the sender generates one, to encrypt the message, then it can't send the key to the recipient because if it does so, any man in the middle would also know the key and thus, making the entire encryption thing useless.

Nice, I don't need to ask "are they holding giant soy sauce bottles"?

Yes, yes they are.

Pass into the ass