Debussy's music is often characterized by impressionist sounds. Its rhythms are often fast and varied, and it's important to be able to master these kinds of styles before moving on to more difficult pieces. For example, Beethoven's Concerto for Piano is a masterpiece of modern art, but it's hardly as popular as the Mozart K332 sonata. Its composition has a rich history and is considered the most popular type of classical piano music.
The Moonlight Sonata by Beethoven is a quiet piece of classical piano music. It was originally called Almost a Fantasy and has been a source of controversy between modern pianists. However, following Beethoven's instructions while using a modern sustain pedal creates dissonance when the chords change. Half-pedaling is an alternative. Both works are innovative and a good start for new piano players. But remember that there are many kinds of classical piano.