Yes as long you use a thing to pay it is called money, so Bitcoin and other cryptocurrecy is a money that thing that it is different with the fiat is it's appearance because bitcoin is a digital currency. So bitcoin is a money and the other alt coin too.
I do not agree with what you say,
bitcoin is not an altcoin, it is a core coin, it is the foundation of all the other altcoins. It's like a common currency of technology, it has the same power and power as cash. Bitcoin is a digital coin that represents the evolution of technology, it is even stronger than many of the current cash in the world.
Yes as long you use a thing to pay it is called money, so Bitcoin and other cryptocurrecy is a money that thing that it is different with the fiat is it's appearance because bitcoin is a digital currency. So bitcoin is a money and the other alt coin too.
Bitcoin is money but its not an altcoin for sure in fact its an foundation of other altcoins as you cannot use any altcoin for buying or getting fiat in hands and if you have to do then first you need to sell your altcoin to bitcoin and then can get fiat currency.
I am sorry guys but it seems that you misunderstood what @Yatsan stated. The bold and underlined portion of his passage, I think, was the source of the misunderstanding.
He/she stated that bitcoin is a money and altcoins are also money. He/she did not say that bitcoin is an altcoin also.