Why use RSA-2048 for plaintext when AES-256 is much more secure? Why do we use RSA encryption for ANY text/communication/data encryption when everybody on internet is writing that AES-256 is much stronger than RSA-2048? If this is true, why do encrypted email services like Protonmail even use RSA encryption for their email communication when it is not as secure as AES-256?

I have read that it is currently impossible to break AES-256 using brute force attacks, but RSA is not such a big problem to break. Why is this method even used in cryptography when it is slower and weaker than a symmetric cipher like AES?

Is the only reason for using RSA is because of its asymmetric geometry (private/public key)?

I know that this question is not easy to answer but I will give one example: 
If I want send secure and encrypted plaintext of - for example - two full A4 pages of text, is it better to use AES-256 or RSA-2048? What I know much stronger and also faster is using AES, but maybe I am missing something?
AES is symmetric encryption.  Both sides must have the same secret key.
RSA is asymmetric encryption.  Each side has a public and private key.  You share your public key so that others can encrypt a message such that only you can read it (with your private key)

There are situations where the key exchange for AES isn't reasonable.  For those situations, we use asymmetric encryption methods like RSA.