It is the other way around - others are terrible pieces of software.
Telegram just works as it expected to. Perfect intuitive UX, flawless features execution, plenty of features both for basic and advanced hardcore users.
One of just few examples of software products that you can call great.
I downloaded Telegram and tried to use it, but it looks like it's not for SMS. More like a discord sort of thing. I'm trying to find a decent SMS app for Android. I don't think one exists anymore.
Also, as soon as I opened the app and got into it one of my contacts began messaging me. I don't know why or how they did it, but I then deleted the app.
sms is the messaging protocol typically used by phones. it's the default for text messages on android. mms is group message and rcs is another protocol.
https://en.wikipedia.org/wiki/SMS
Looks like you still new to this new generation of messaging apps.
They are far away from oldschool SMS -> they send messages over internet but connect people based on their contact lists (phone numbers users sign up with).
Also have to use whatsapp once in a while because some relatives and friends prefer familiarity to quality.