bitcoin is only one while altcoin in large numbers on one hand has different functions.
so it's no surprise that bitcoin is the key to all this, including ways to introduce other cryptoqurrency as well.
I mean, if people know bitcoin automatically, people will also know about other cryptocurrency.
Absolutely correct, it's like a domino effect so once people have been exposed to Bitcoin then they will surely know about other cryptocurrencies though it will take some years from now and altcoins should have big development like having a real use-case or stopped the scummy project to gain trust from people or investors.