3:2 is the perfect fifth. 2:1 is the octave. Hence if you climb (or descend) by perfect fifths you never align with the notes you get if you climb (descend) by octaves.
Look up "just intonation" and "equal temperament" if you are interested. Also "The Well-Tempered Clavier" is highly recommended for listening!
Just a side note: "The Well-Tempered Clavier" is not at all the same as the "Equally Tuned Piano".
Bach was certainly aware of the equal tuning, where all intervals were the same. It had been used on lutes for some centuries. But with harpsichords, and to some extent pipe organs, an equal temperament was not what Bach or his contemporaries wanted - it didn't have a single pure interval!
Look up "just intonation" and "equal temperament" if you are interested. Also "The Well-Tempered Clavier" is highly recommended for listening!