What do you call a person who is always ready and keen to learn new things?
You might use:
The closest word I can think of would be receptive or eager. However, for preciseness, you should say eager to learn new things.
You could call them "curious".
If you are looking for a noun, the best would be probably be polymath, or at least one seeking to become one.
Polymath a person of wide-ranging knowledge or learning