I do believe that everyone, without regardless of an age is able to develop some basic skills of piano technique which could help to play at least some less complicated pieces.
It is long term a process which could be compare with learning of reading or learning of foreign language.
The process is not easy and requires many hours of daily practice. It requires dedication and sacrifice.
The piano technique is an art of coordination a human mussels and properly apply them during playing a piano.
This great foundation provides a freedom and make possible to focus on interpretation.
I do believe that demonstration is very important in music teaching and sometimes is worth more than a thousand words.
A good teacher in my opinion is that who not only corrects the mistakes but that who can listen and is open for discussion.