I have read many replies and I don't think there is one good reply that would have cured OP curiosity. The cryptocurrcency is word that comes from cryptography, most of the early altcoins used cryptography to work, it makes sense to say all coins are cryptocurrcency even though there other few coins that don't make use of cryptography. However, Bitcoin is unique in many ways that's why you can't compare it to other coins, it never had a single team and yet the most successful.
You made a point but you also admitted that it make sense to say all coins are cryptocurrency I don’t the see why you refrained from that statement and exempt bitcoin in your second paragraph.
Most developers grow up to understand Bitcoin as Bitcoin, there was nothing like cryptocurrcency when Bitcoin was even created, it's not even in the whitepaper, it was later when altcoins became known and popular that cryptocurrcency as a word become norm and now they used it for all coins in the market. It's good for the market, outsiders that don't know what they look like used it to identify but I'm not sure if Bitcoin make sense to be called as crypto or cryptocurrcency.
Cryptocurrency is just a word that is used in digital world as digital form of money that exists only electronically, I am not sure if it wasn’t mentioned in the white papers but there is no a way and address can be generated without making use of cryptography, you can not remove bitcoin and say it is not a cryptocurrency because it uses cryptography tool like the ECDSA, SHA-256 and many other.
Bitcoin may behave differently from other alternatives coin but I believe every form of money that isn’t physical but works only electronically with those cryptography tool built in it design should be regarded as cryptocurrency and bitcoin isn’t an exemption