Everyone knew about James and Lily Potter. They were heroes, celebrated for fighting against You-Know-Who. Names commemorated for being the parents of the one that ultimately killed him. Remembered for protecting their son 'til they died. They were perfect, untouchable because of their deeds. Martyrs. Everyone knew them because of their deaths, but so few can remember their lives.
Most of those few are gone now too.
They weren't perfect. No one is, but people have a way of forgetting that when you sacrifice your life for your child. Lily Evans-Potter had a temper: kind and gracious, but Merlin help you if you anger her. James Potter was proud, reckless, and arrogant. (He toned it down a bit in 7th year, which was why Lily finally said yes.)
They weren't perfect, but I suppose that's why they loved each other.
They'd hate it if they knew that all anyone remembered them doing was dying. They'd hate the fact that no one knew about all the not-so-honourable things that they did, like that time Lily screamed at James in front of the entire year when they had a fight, or when James took a prank too far in their 4th year and sent Lily to the Hospital Wing. They hated perfection, mostly because neither of them had it, and I'm fairly sure James delivered an interesting rant about it once, but no one knows about that either.
I definitely don't. I wish I did. I wish I knew my parents and all their deeds, good or bad, but all I can do is scratch half-attempted words on parchment. I don't know what their fights had been about, or what rants my father delivered, or whether my mum can cook (Sirius said Dad only ever ate her cookies lest she hex him), but I can take a guess.
It's better than having their exceptionally short, extraordinarily vivid lives omitted from those history books.
At least I think that's how Mum would put it.