[drdeca]

Do you know linear algebra?

If you have a collection of n qubits, the state of those corresponds to a unit vector in a 2^n dimensional space over the field of complex numbers.

You can do certain linear operations (iirc, only unitary ones. I wouldn’t claim all unitary ones either) to change the state. You can also do a measurement, which has a random outcome, following the Born rule.

So, it isn’t really just “each of them has more than 2 possible states”. That can be the case with something classical, and has been done before (there have been ternary computers. Binary computers won out. Ternary computers (or quaternary, etc. etc.) wouldn’t be particularly special.)

You can’t just think of each of the qubits as having a state always entirely independent of the rest of the qubits.