Money is also a commodity, but one with specific properties.
The main two properties that turn a commodity into money are:
- "store of value": that is, the main (or sole) reason to acquire it, is the speculative expectation to sell it later against valuable goods and services. In other words, you acquire the commodity essentially only for speculative purposes, and not to use it as a consumption good, or as a capital (production) good.
- "high tradability": it should be a commodity that is in universal demand, and that is easily traded against most anything.
Clearly, bitcoin is realizing (up to a point) the first aspect. The second aspect will come if there is generalized merchant adoption.
Those are two of the functions of money. Properties of money being durability, divisibility, fungibility, compactness, easy to recognize, difficult to forge.
Not necessary by design - stuff with those properties tend to be chosen as money by people engaged in trade.