Sonic 1 was just a bad game. Sonic 2 just instantly felt so much smoother and so much easier to play, the level design was a billion times better, didn't have a ton of super cheap enemies to jump out of nowhere to get you.
Sonic 2 wasn't a bunch of hurry up & wait like the original, no underwater levels that make you have to wait for bubbles to pop up so Sonic can breathe again.
i think a lot of Sonic 1's flaws were the Sonic Team trying to figure out what they were doing, but i don't wanna blame them.
It's not Sonic Team's fault because they were under pressure and probably completely bogged down by Sega themselves because Sega had to compete against Mario.
the people in Sonic Team were decent people, but Sonic 1 the game itself sucks.
The only two things that made Sonic 1 memorable was the marketing and people liking the Green Hill Zone.