Bitcoin is not a cryptocurrency don't mislead newbies here bitcoin is bitcoin while shitcoins is shitcoins moreover this is a bitcoin discussion thread so you can take your Crypto elsewhere.
Unless you are advising investor or newbies not to invest into shitcoins rather than bitcoin investment which their discretionary income and hodl bitcoin for long either using the DCA strategy to stack bitcoin buying either weekly or monthly and hodl rather than fucking around shitcoins.
Personally, if you say that Bitcoin is not part of cryptocurrencies, I think that assumption is also inaccurate. Because as far as I know, those that use blockchain technology or cryptography can be said to be part of crypto currency. So bitcoin can also be called part of crypto, because bitcoin also uses blockchain technology and in fact bitcoin is the one who pioneered it. But what differentiates bitcoin from other cryptocurrencies is its quality alone. Because it cannot be denied that what we call shitcoin has quite bad quality. So it wouldn't be good if used as an investment. In contrast to bitcoin, bitcoin has a decentralized system and also has a high level of security that will be difficult for any cybercriminal to penetrate. That's why bitcoin is superior to shitcoin. And it's true that instead of trading in shitcoins, it's definitely better to invest in bitcoin. Because investing in bitcoin has very minimal risk and playing with shitcoins is very risky. So we really have to stay away from shitcoins and keep investing in bitcoin.
You are making sense though but the truth is Bitcoin is still a part of cryptocurrency but for the sake of newbie here it won't be good to be addressing it as a cryptocurrency because this can make them to invest in shitcoin thinking that they are all same thing which may result to a loss or gain depending so it will be wise if we don't classified or categorize Bitcoin in cryptocurrency. However, one of the difference you didn't mentioned that makes Bitcoin so special is the potential of it and not just quality as you mentioned because
some other shitcoin has quality and no investment is risk free but the risk in Bitcoin investment is very minimal and if you should hold for a long period of time with consistent accumulation you will make a good return.
What quality does some other shitcoins have when they are dependent on Bitcoin? All shitcoins are just shitcoins.